Make mysql compilable on gcc-4.2.1.

c++config.h now has the following code:
// For example, <windows.h> is known to #define min and max as macros...
#undef min
#undef max

So, our defines in my_global.h are undefined when <new> header
is included.

Move definitions of min()/max() to the end of my_global.h.

include/my_global.h

@@ -562,12 +562,6 @@ int	__void__;
 #define PURIFY_OR_LINT_INIT(var)
 #endif
 
-/* Define some useful general macros */
-#if !defined(max)
-#define max(a, b)	((a) > (b) ? (a) : (b))
-#define min(a, b)	((a) < (b) ? (a) : (b))
-#endif
-
 #if !defined(HAVE_UINT)
 #undef HAVE_UINT
 #define HAVE_UINT
@@ -1508,4 +1502,10 @@ inline void  operator delete[](void*, void*) { /* Do nothing */ }
 /* Length of decimal number represented by INT64. */
 #define MY_INT64_NUM_DECIMAL_DIGITS 21
 
+/* Define some useful general macros (should be done after all headers). */
+#if !defined(max)
+#define max(a, b)	((a) > (b) ? (a) : (b))
+#define min(a, b)	((a) < (b) ? (a) : (b))
+#endif
+
 #endif /* my_global_h */