wxCALL_FOR_EACH compilation fix for VC++.

VC++ has a bug where __VA_ARGS__ is incorrectly expanded as a single
token, contrary to C99. The solution is to pass the arguments to another
macro as a single token inside parenthesis.

See http://stackoverflow.com/questions/9183993/msvc-variadic-macro-expansion
for the gory details.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72850 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775