Core: removed incorrect GCC 2.7 check.

It was broken since introduction (__GNU__ instead of __GNUC__) and did
nothing.  Moreover, GCC 2.7 is happy with the normal version of the code.

Reported by Joel Cunningham,
http://mailman.nginx.org/pipermail/nginx-devel/2016-March/007964.html.
diff --git a/src/core/ngx_config.h b/src/core/ngx_config.h
index 145e43a..a0bfa63 100644
--- a/src/core/ngx_config.h
+++ b/src/core/ngx_config.h
@@ -125,12 +125,7 @@
 #endif
 
 
-#if ((__GNU__ == 2) && (__GNUC_MINOR__ < 8))
-#define NGX_MAX_UINT32_VALUE  (uint32_t) 0xffffffffLL
-#else
 #define NGX_MAX_UINT32_VALUE  (uint32_t) 0xffffffff
-#endif
-
 #define NGX_MAX_INT32_VALUE   (uint32_t) 0x7fffffff