Pigeonhole-0.5.7 fails to build from sources

[Lefteris Tsintjelis]

Latest update fails to build from sources in FreeBSD 12-STABLE

--- lda-sieve-plugin.lo ---
lda-sieve-plugin.c:82:27: error: variable has incomplete type 'struct 
smtp_submit_input'
         struct smtp_submit_input submit_input;
                                  ^
lda-sieve-plugin.c:82:9: note: forward declaration of 'struct 
smtp_submit_input'
         struct smtp_submit_input submit_input;
                ^
1 error generated.
*** [lda-sieve-plugin.lo] Error code 1

make[6]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7/src/plugins/lda-sieve
--- lda-sieve-log.lo ---
mv -f .deps/lda-sieve-log.Tpo .deps/lda-sieve-log.Plo
1 error

make[6]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7/src/plugins/lda-sieve
*** [all-recursive] Error code 1

make[5]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7/src/plugins
1 error

make[5]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7/src/plugins
*** [all-recursive] Error code 1

make[4]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7/src
1 error

make[4]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7/src
*** [all-recursive] Error code 1

make[3]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7
1 error

make[3]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7
*** [all] Error code 2

make[2]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7
1 error

make[2]: stopped in 
/usr/ports/mail/dovecot-pigeonhole/work/dovecot-2.3-pigeonhole-0.5.7
===> Compilation failed unexpectedly.
Ensure that dovecot-pigeonhole's GSSAPI backend is the same as dovecot2 
(make
config). Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the
failure to the maintainer.
*** Error code 1

Stop.
make[1]: stopped in /usr/ports/mail/dovecot-pigeonhole
*** Error code 1

Stop.
make: stopped in /usr/ports/mail/dovecot-pigeonhole