Fixed assembly relocation problems, so we can check for NASM on Mac OS X.

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%402396

configure.in

@@ -2503,10 +2503,7 @@ case "$host" in
         CheckDiskAudio
         CheckDummyAudio
         CheckDLOPEN
-
-        # Temporarily disabled:
-        # ld: mmxp2_32.o has external relocation entries in non-writable section (__TEXT,__text) for symbols: _mmxreturn
-        #CheckNASM
+        CheckNASM
 
         # Set up files for the shared object loading library
         # (this needs to be done before the dynamic X11 check)