Use some wxX11 files (currently pen.cpp and brush.cpp) in wxMotif.

  Use some wxX11 files (currently pen.cpp and brush.cpp) in wxMotif.
  Add src/x11 to VPATH in configure, and add a new flag to filelist.txt
indicating a file used in wxMotif but not in wxMotif directory.
  Modifed VMS makefiles, too (should be checked by someone with VMS,
though).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@19265 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775