Remove wrong export CheckFullscreen


git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6563 4407c894-4637-0410-b4f5-ada5f102cad1
Remove illegal export CheckFullscreen


git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6564 4407c894-4637-0410-b4f5-ada5f102cad1
merge from trunk r6563/6564 - lib64/ddraw.def, lib64/d3d9.def: Remove illegal export CheckFullscreen

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6565 4407c894-4637-0410-b4f5-ada5f102cad1