libcompat: put snprintf defines in libcompat.h
libcompat: put snprintf defines in libcompat.h

On MSVC, the cmake definitions do not seem to work as expected.
Putting the snprintf and vsnprintf definitions in libcompat.h.

git-svn-id: ae38cf1093b87151f738d2b2220cac7742ad2e55@996 64e312b2-a51f-0410-8e61-82d0ca0eb02a

lubosz/check,lubosz/check,lubosz/check,lubosz/check