Try to use the int32 and friends on all Unixes -- not just SGI's Irix.
--- icc34.h	Tue Feb 13 12:08:06 2001
+++ icc34.h	Wed Sep  5 10:08:42 2001
@@ -141,8 +141,10 @@
  * etc into icXXX form. The rest of the header uses the icXXX
  * typedefs. Signatures are 4 byte quantities.
  */
+#ifdef __unix__
 #ifdef __sgi
 #include "sgidefs.h"
+#endif
 
 typedef __int32_t       icSignature;