Finally I've got a snapshot. The build on AIX went OK except 2 issues (actually, I had them during previous builds but unfortunately didn't have time to report all details):
1) "Macro redefinition..." error for FD_SET(n, p), FD_CLR(n, p), FD_ISSET(n, p) and FD_ZERO(p) in .../src/remote/inet.cpp
Exactly the same definitions for these macros exist on AIX in /sys/time.h, so I just embraced all 4 with corresponding #ifndef / #endif to resolve the problem. In my understanding, it shouldn't hurt other platforms.
2) Error processing ./builds/posix/empty.vers file, like:
xlC_r -q64 -gxlc -D_REENTRANT -bE:../builds/posix/empty.vers -D_THREAD_SAFE -blibpath:/usr/local/firebird/lib:/usr/local/firebird/intl:/usr/local/lib:/usr/lib:/lib -brtl ../temp/std/remote/server_stub.o -o ../gen/firebird/bin/fb_inet_server -L../gen/firebird/lib -lfbembed -lm -lpthreads
ld: 0706-027 The -x flag is ignored.
ld: 0711-151 SEVERE ERROR: EXPORTS: Invalid option name: VERSION
ld: 0711-151 SEVERE ERROR: EXPORTS: Invalid option name: SCRIPT
ld: 0711-418 ERROR: Import or export file ../builds/posix/empty.vers at line 24:
A symbol name may only be followed by an export attribute
or an address. The line is being ignored.
It looks like xlC_r do not treat lines started with '#' as comments. I just removed these lines, but may be you know more elegant way to resolve it.