Add wxHAS_LONG_LONG_T_DIFFERENT_FROM_LONG symbol.

Instead of writing a rather unreadable "defined(wxLongLong_t) &&
!defined(wxLongLongIsLong)" expression every time we need to decide if a
function needs to be overloaded for both long and long long, add a new symbol
which can be tested directly.

No real changes in the code.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66711 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/defs.h

@@ -1075,6 +1075,9 @@ typedef wxUint32 wxDword;
 
     #define wxHAS_INT64 1
 
+    #ifndef wxLongLongIsLong
+        #define wxHAS_LONG_LONG_T_DIFFERENT_FROM_LONG
+    #endif
 #elif wxUSE_LONGLONG
     /*  these macros allow to define 64 bit constants in a portable way */
     #define wxLL(x) wxLongLong(x)