Restore correct setting of the background colour.

Restore correct setting of the background colour.

The background colour for the HDC used for drawing the native controls wasn't
set correctly any more after changes of r61859 but we do need to call it or
the text in edit and similar controls is drawn using the default background
even if we return the correct brush which is used for erasing the control.

Closes #11190.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61885 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775