Test for __MINGW64_TOOLCHAIN__ and not __MINGW64__ in wx/filefn.h.

MinGW-w64 headers are the same in 32 and 64 bit cases, so test for these
headers presence with __MINGW64_TOOLCHAIN__ and not for 64 bit build with
__MINGW64__, which should probably not be used anywhere at all.

This fixes problems with wx{Rm,Mk}dir() definitions with MinGW-w64 in
non-Unicode build.

Closes #16362.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77536 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add wxBitmap ctor from wxCursor to wxGTK and wxMSW.

Allow converting wxCursor to wxBitmap in order to draw it, for example.

Closes #15699.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77537 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Deprecate wxBitmap assignment operator from wxCursor in wxMSW.

This assignment operator is not portable and a better alternative is available
now with the addition of the wxBitmap ctor from wxCursor in the previous
commit.

See #15699.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77538 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Don't say that 15+ year old wxDateTime is relatively new.

Update the description of wxUSE_DATETIME in various setup.h files for the 21st
century.

Closes #16523.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77539 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add default values for wxRichMessageDialog ctor arguments.

Both "caption" and "style" arguments were documented as having default values,
but didn't really have them. Fix this by actually adding them.

Closes #16524.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77540 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775