I had this problem trying to compile Interclient on AIX:

cc -c -qchars=signed -O -DHADES -DPROD_BUILD interface.c
cc: unrecognized option `-qchars=signed'
In file included from ../jrd/license.h:49,
from interface.c:41:
../jrd/build_no.h:5:28: warning: null character(s) preserved in
literal
../jrd/build_no.h:6:25: warning: null character(s) preserved in
literal
In file included from interface.c:55:
../jrd/sdl_proto.h:27: warning: `struct ads' declared inside
parameter list
../jrd/sdl_proto.h:27: warning: its scope is only this definition or
declaration
, which is probably not what you want.
../jrd/sdl_proto.h:30: warning: `struct ads' declared inside
parameter list
interface.c: In function `REM_fetch':
interface.c:1842: `ALIGNMENT' undeclared (first use in this function)
interface.c:1842: (Each undeclared identifier is reported only once
interface.c:1842: for each function it appears in.)
interface.c: In function `REM_free_statement':
interface.c:1903: warning: cast to pointer from integer of different
size
interface.c: In function `REM_get_segment':
interface.c:2388: `ALIGNMENT' undeclared (first use in this function)
interface.c: In function `REM_put_segment':
interface.c:2778: `ALIGNMENT' undeclared (first use in this function)
interface.c: In function `REM_receive':
interface.c:3183: `ALIGNMENT' undeclared (first use in this function)
make: 1254-004 The error code from the last command is 1.