remove obsolete ROS externals, contents moved to git at http://git.reactos.org/?p=reactos.git;a=tree;f=reactos/include;h=bb2902454e40607cb00fc02671d3f04658d1e085;hb=HEAD

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6377 4407c894-4637-0410-b4f5-ada5f102cad1
merge of r6297 through r6377 from trunk

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6378 4407c894-4637-0410-b4f5-ada5f102cad1