Compilation fixes for wide char functions under IRIX with mipsPro.

Compilation fixes for wide char functions under IRIX with mipsPro.

Use correct (XPG5, not XPG4) version of wcsftime().

Bring the wide char functions only declared in std namespace into global one
under IRIX.

Declare vswscanf() ourselves as we just don't seem to get its declaration from
C++ code (only from C99).

Add a cast to fix incorrect putws() signature.

All these fixes apply to IRIX 6.5.18 with mipsPro 7.4.2. It doesn't seem to
add configure checks for most of the above fixes as previous versions of both
the OS and the compiler should be completely extinct by now but we may need to
do it if anybody is still found to use them.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63583 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775