Fix __attribute__ changes.

It cannot be checked with #ifndef, if you really think about what it
does which cannot be done only with the preprocessor.  My thinko.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

cache.h

@@ -38,11 +38,10 @@
 #define NORETURN __attribute__((__noreturn__))
 #else
 #define NORETURN
-#endif
-
 #ifndef __attribute__
 #define __attribute__(x)
 #endif
+#endif
 
 /*
  * Intensive research over the course of many years has shown that