NOTE: some suns seems to require -DUSE_STANDARD_MALLOC, otherwise you get
a bus error in color-make at runtime.
vax: -DSTUPID
sm90: -DSTUPID -DSYSV
dpx: -DSYSV
Hp9000 -DSYSV +Ns2000 +Nd2000
IBM RS6000/AIX: -DSYSV -DDO_NOT_DECLARE_STRCHR -DNEED_SELECT_H
IBM/RT: -DSYSV -DIBM_RT -Nn3000
SGI Irix 5.3: -DSVR4 -DNO_STRUCTURE_OFFSETS
Unixware: -DSVR4 -DDO_NOT_REDEFINE_MALLOC
linux: same flags as set by you xmkmf, e.g: -O2 -m486 -ansi -DNO_ASM -I/usr/X11R6/include/X11/extensions -I/usr/X11R6/include -Dlinux -D__i386__ -D_POSIX_SOURCE -D_BSD_SOURCE -D_GNU_SOURCE -DFUNCPROTO=15 -DNARROWPROTO