Add "Mac OS" support

build/config.guess

@@ -1018,7 +1018,7 @@ EOF
     *:Rhapsody:*:*)
 	echo ${UNAME_MACHINE}-apple-rhapsody${UNAME_RELEASE}
 	exit 0 ;;
-    *:Darwin:*:*)
+    *:Darwin:*:* | *:"Mac OS":*:*)
 	echo `uname -p`-apple-darwin${UNAME_RELEASE}
 	exit 0 ;;
     *:procnto*:*:* | *:QNX:[0123456789]*:*)