check for __ia64__ when setting USE_IEEE

src/mesa/main/imports.h

@@ -223,6 +223,7 @@ extern void _ext_mesa_free_pixelbuffer( void *pb );
  ***/
 #if defined(__i386__) || defined(__386__) || defined(__sparc__) || \
     defined(__s390x__) || defined(__powerpc__) || defined(__AMD64__) || \
+    defined(__ia64__) || \
     ( defined(__alpha__) && ( defined(__IEEE_FLOAT) || !defined(VMS) ) )
 #define USE_IEEE
 #define IEEE_ONE 0x3f800000