Prevent features.h from being "fixed" when compiling gcc

Newer gcc versions fix that header file, and place a copy in gccs
private include-fixed directory. But we need to support also older compilers,
and that prevents us from updating the file by newer versions of mintlib.

The fix just adds a space, so the pattern in fixincludes just does not match.

include/features.h.in

@@ -584,7 +584,7 @@
 
 /* Decide whether we can define 'extern inline' functions in headers.  */
 #if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ \
-    && !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__
+    &&  !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__
 # define __USE_EXTERN_INLINES	1
 # if (defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__) || \
      defined __cplusplus || \