Add wxASSERT_MSG_AT() and wxFAIL_MSG_AT() macros.

These macros are useful for functions called from other macros to allow
pretending that an assert inside such function actually happens at the point
in the sources where the macro itself appears.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78409 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -53,6 +53,7 @@ All:
 - Allow recursive calls to wxYield().
 - Add wxART_FULL_SCREEN standard bitmap (Igor Korot).
 - Fix wxStringTokenizer copy ctor and assignment operator.
+- Added wxASSERT_MSG_AT() and wxFAIL_MSG_AT() macros.
 
 Unix: