I tried to build openssh-3.2.3p1 on IRIX using:
 > env CC=cc CFLAGS="-n32 -mips3" LDFLAGS="-n32 -mips3" ./configure
 > gmake

This works perfectly well with openssh-3.1p1, but fails for 3.2.3p1:
...
        (cd openbsd-compat && make)
        cc -n32 -mips3 -I. -I. -I/opt/TWWfsw/libopenssl09//include 
-I/usr/local/include -DSSHDIR=\"/usr/local/etc\" 
-D_PATH_SSH_PROGRAM=\"/usr/local/bin/ssh\" 
-D_PATH_SSH_ASKPASS_DEFAULT=\"/usr/local/libexec/ssh-askpass\" 
-D_PATH_SFTP_SERVER=\"/usr/local/libexec/sftp-server\" 
-D_PATH_SSH_PIDDIR=\"/usr/local/etc\" 
-D_PATH_PRIVSEP_CHROOT_DIR=\"/var/empty\" 
-DSSH_RAND_HELPER=\"/usr/local/libexec/ssh-rand-helper\" -DHAVE_CONFIG_H -c
monitor_fdpass.c
cc-1275 cc: WARNING File = defines.h, Line = 115
  The indicated "typedef" name has already been declared (with same type).

  typedef unsigned int u_int;
                       ^

cc-1275 cc: WARNING File = defines.h, Line = 215
  The indicated "typedef" name has already been declared (with same type).

  typedef unsigned char u_char;
                        ^

cc-1020 cc: ERROR File = monitor_fdpass.c, Line = 58
  The identifier "SCM_RIGHTS" is undefined.

        cmsg->cmsg_type = SCM_RIGHTS;
                          ^

cc-1020 cc: ERROR File = monitor_fdpass.c, Line = 117
  The identifier "SCM_RIGHTS" is undefined.

        if (cmsg->cmsg_type != SCM_RIGHTS)
                               ^

I checked /usr/include/sys/socket.h and found:
...
#ifdef _XOPEN_SOURCE
/* "Socket"-level control message types: */
#define SCM_RIGHTS      0x01            /* access rights (array of int) */
#endif /* _XOPEN_SOURCE */
...

Thus I tried this cc command with an additional -D_XOPEN_SOURCE, but this fails
with a lot more (21) errors like: "ulong is undefined" ... "u_short is
undefined" ... 

I didn't try gcc yet.

Olaf.