building Dovecot in Debian 9

[KT Walrus]

> On Apr 25, 2017, at 5:37 PM, KT Walrus <kevin at my.walr.us> wrote:
> 
> Also, I spotted a deprecation warning that you might want to look into since it has to do with building against OpenSSL 1.1 (which is the default version for Debian 9).

Oops!!!

Forgot to attach the warning:

libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I../.. -I../../src/lib -I../../src/lib-test -DMODULE_DIR=\"/usr/lib/dovecot\" -std=gnu99 -g -O2 -Wall -W -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith -Wchar-subscripts -Wformat=2 -Wbad-function-cast -fno-builtin-strftime -Wstrict-aliasing=2 -MT iostream-openssl-params.lo -MD -MP -MF .deps/iostream-openssl-params.Tpo -c iostream-openssl-params.c  -fPIC -DPIC -o .libs/iostream-openssl-params.o
^[[91miostream-openssl-params.c: In function 'generate_dh_parameters':
^[[0m^[[91miostream-openssl-params.c:18:2: warning: 'DH_generate_parameters' is deprecated [-Wdeprecated-declarations]
  dh = DH_generate_parameters(bitsize, DH_GENERATOR, NULL, NULL);
  ^~
^[[0m^[[91mIn file included from /usr/include/openssl/dh.h:13:0,
                 from /usr/include/openssl/dsa.h:31,
                 from /usr/include/openssl/x509.h:32,
                 from /usr/include/openssl/ssl.h:50,
                 from iostream-openssl.h:6,
                 from iostream-openssl-params.c:5:
/usr/include/openssl/dh.h:118:1: note: declared here
 DEPRECATEDIN_0_9_8(DH *DH_generate_parameters(int prime_len, int generator,
 ^