"@LIBICU_CFLAGS@: No such file or directory" during libtool command for lib-fts (cross compile)

[awl1]

Hello,

I am a complete newbie to dovecot, but do have reasonable experience in 
compiling Unix/Linux software.

I am currently trying to do a cross-compile of dovecot-2.29.1 to be used 
on my home office Thecus NAS (host: Thecus kernel 2.6.33 on 32-bit Intel 
Atom: "i686-nptl-linux-gnu"; my build machine has Ubuntu 16.04.2 LTS) 
"from ground up", i.e. I need to build and provide all dovecot 
dependencies from within my module.

My compiler toolchain (using gcc-5.2.0) has been set up properly using 
ct-ng and works completely fine.

I also have already successfully cross-compiled/built almost all dovecot 
dependencies (zlib, bzip2, xz, lz4, openssl-1.0.2, clucene-git, 
snowball-git, libexttextcat, icu) - i.e. including icu - and installed 
them properly into my cross-compile build root 
(/raid/data/module/Dovecot/sys as defined by Thecus module spec).

My dovecot configure/make command is as follows:

===
export PKG_CONFIG=/usr/bin/pkg-config
export PKG_CONFIG_PATH=/raid/data/module/Dovecot/sys/lib/pkgconfig

export 
CC=$HOME/Thecus/n4200pro-5.2.0-toolchain/i686-nptl-linux-gnu/bin/i686-nptl-linux-gnu-gcc
export CFLAGS=""

export LDFLAGS="-L/raid/data/module/Dovecot/sys/lib 
-Wl,-rpath,/raid/data/module/Dovecot/sys/lib"
export LIBS="" # -llib

export CPPFLAGS=-I/raid/data/module/Dovecot/sys/include
export 
CPP=$HOME/Thecus/n4200pro-5.2.0-toolchain/i686-nptl-linux-gnu/bin/i686-nptl-linux-gnu-cpp

export 
CXX=$HOME/Thecus/n4200pro-5.2.0-toolchain/i686-nptl-linux-gnu/bin/i686-nptl-linux-gnu-g++
export CXXFLAGS=""

export LT_SYS_LIBRARY_PATH=/raid/data/module/Dovecot/sys/lib

export 
CXXCPP=$HOME/Thecus/n4200pro-5.2.0-toolchain/i686-nptl-linux-gnu/bin/i686-nptl-linux-gnu-cpp

./configure --host i686-nptl-linux-gnu \
             --prefix=/raid/data/module/Dovecot/sys \
             --libdir=/raid/data/module/Dovecot/sys/lib \
             --localstatedir=/raid/data/module/Dovecot/com \
             --sharedstatedir=/raid/data/module/Dovecot/var \
             --disable-silent-rules \
             --with-notify=inotify \
             --with-lucene \
             --with-stemmer \
             --with-textcat \
             --with-icu \
             --with-solr \
             --with-zlib \
             --with-bzlib \
             --with-lzma \
             --with-ssl=openssl \
             --with-ssldir=/raid/data/module/Dovecot/sys/etc/ssl \
--with-storages=mdbox,sdbox,maildir,mbox,cydir,imapc,pop3c \
             --with-moduledir=/raid/data/module/Dovecot/sys \
             --with-gnu-ld \
             --with-sysroot=/raid/data/module/Dovecot/sys \
             --with-libiconv-prefix=/raid/data/module/Dovecot/sys \
             --with-libintl-prefix=/raid/data/module/Dovecot/sys

make
===

and completes configuration just fine, but the make step runs into the 
following issue which I am unable to resolve even after several hours of 
investigation, so I am completely stuck at this point... :-(

===
(...)
make[3]: Leaving directory 
'/home/andreas/Thecus/Dovecot/dovecot-2.2.29.1/src/lib-dovecot'
Making all in lib-fts
make[3]: Entering directory 
'/home/andreas/Thecus/Dovecot/dovecot-2.2.29.1/src/lib-fts'
make  all-am
make[4]: Entering directory 
'/home/andreas/Thecus/Dovecot/dovecot-2.2.29.1/src/lib-fts'
/bin/bash ../../libtool  --tag=CC   --mode=compile 
/home/andreas/Thecus/n4200pro-5.2.0-toolchain/i686-nptl-linux-gnu/bin/i686-nptl-linux-gnu-gcc 
-DHAVE_CONFIG_H -I. -I../..  -I../../src/lib -I../../src/lib-test 
-I../../src/lib-mail -I../../src/lib-fts 
-I/raid/data/module/Dovecot/sys/include/libexttextcat/ @LIBICU_CFLAGS@ 
-DUDHRDIR=\""../../src/lib-fts"\" 
-DDATADIR=\"/raid/data/module/Dovecot/sys/share/dovecot\" 
-DTEST_STOPWORDS_DIR=\""../../src/lib-fts/stopwords"\" 
-I/raid/data/module/Dovecot/sys/include  -std=gnu99  -Wall -W 
-Wmissing-prototypes -Wmissing-declarations -Wpointer-arith 
-Wchar-subscripts -Wformat=2 -Wbad-function-cast -fno-builtin-strftime 
-Wstrict-aliasing=2 -I/raid/data/module/Dovecot/sys/include  -MT 
fts-filter.lo -MD -MP -MF .deps/fts-filter.Tpo -c -o fts-filter.lo 
fts-filter.c
libtool: compile: 
/home/andreas/Thecus/n4200pro-5.2.0-toolchain/i686-nptl-linux-gnu/bin/i686-nptl-linux-gnu-gcc 
-DHAVE_CONFIG_H -I. -I../.. -I../../src/lib -I../../src/lib-test 
-I../../src/lib-mail -I../../src/lib-fts 
-I/raid/data/module/Dovecot/sys/include/libexttextcat/ @LIBICU_CFLAGS@ 
-DUDHRDIR=\"../../src/lib-fts\" 
-DDATADIR=\"/raid/data/module/Dovecot/sys/share/dovecot\" 
-DTEST_STOPWORDS_DIR=\"../../src/lib-fts/stopwords\" 
-I/raid/data/module/Dovecot/sys/include -std=gnu99 -Wall -W 
-Wmissing-prototypes -Wmissing-declarations -Wpointer-arith 
-Wchar-subscripts -Wformat=2 -Wbad-function-cast -fno-builtin-strftime 
-Wstrict-aliasing=2 -I/raid/data/module/Dovecot/sys/include -MT 
fts-filter.lo -MD -MP -MF .deps/fts-filter.Tpo -c fts-filter.c  -fPIC 
-DPIC -o .libs/fts-filter.o
i686-nptl-linux-gnu-gcc: error: @LIBICU_CFLAGS@: No such file or directory
Makefile:714: recipe for target 'fts-filter.lo' failed
make[4]: *** [fts-filter.lo] Error 1
make[4]: Leaving directory 
'/home/andreas/Thecus/Dovecot/dovecot-2.2.29.1/src/lib-fts'
Makefile:562: recipe for target 'all' failed
===

As far as I can tell, my pkgconfig file 
(/raid/data/module/Dovecot/sys/lib/pkgconfig/icu-i18n.pc) also seems to 
be fine:

===
# Copyright (C) 2016 and later: Unicode, Inc. and others.
# License & terms of use: http://www.unicode.org/copyright.html
# Copyright (C) 2010-2013, International Business Machines Corporation. 
All Rights Reserved.

# CFLAGS contains only anything end users should set
CFLAGS =
# CXXFLAGS contains only anything end users should set
CXXFLAGS =  -std=c++11
# DEFS only contains those UCONFIG_CPPFLAGS which are not auto-set by 
platform.h
DEFS =
prefix = /raid/data/module/Dovecot/sys
exec_prefix = ${prefix}
#bindir = ${exec_prefix}/bin
libdir = ${exec_prefix}/lib
includedir = ${prefix}/include
baselibs = -lpthread -ldl -lm
#datarootdir = ${prefix}/share
#datadir = ${datarootdir}
#sbindir = ${exec_prefix}/sbin
#mandir = ${datarootdir}/man
#sysconfdir = ${prefix}/etc
UNICODE_VERSION=9.0
ICUPREFIX=icu
ICULIBSUFFIX=
LIBICU=lib${ICUPREFIX}
#SHAREDLIBCFLAGS=-fPIC
pkglibdir=${libdir}/icu${ICULIBSUFFIX}/59.1
#pkgdatadir=${datadir}/icu${ICULIBSUFFIX}/59.1
ICUDATA_NAME = icudt59l
#ICUPKGDATA_DIR=${exec_prefix}/lib
#ICUDATA_DIR=${pkgdatadir}
ICUDESC=International Components for Unicode

Version: 59.1
Cflags: -I${includedir}
# end of icu.pc.in
Description: International Components for Unicode: Internationalization 
library
Name: icu-i18n
Requires: icu-uc
Libs: -licui18n
===

Note that even adding a line stating

LIBICU_CFLAGS=-I/raid/data/module/Dovecot/sys/include

(just in order to set it to any non-null value) to the icu-i18n.pc file 
and/or setting an environment variable

export LIBICU_CFLAGS=-I/raid/data/module/Dovecot/sys/include

before running configure does NOT help to get rid of the above error...

So do you have any idea why variable substitution for LIBICU_CFLAGS does 
not work, and what could be done to work around this?

Many thanks in advance for your kind help with this!
Best regards,

Andreas
awl1 at gmx.net