Update OpenGL headers from upstream

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6611 4407c894-4637-0410-b4f5-ada5f102cad1
Add myself to AUTHORS

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6612 4407c894-4637-0410-b4f5-ada5f102cad1
Define _ALLOCA_S_MARKER_SIZE on ARM

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6613 4407c894-4637-0410-b4f5-ada5f102cad1
Don't care about x86 acceleration instruction sets on non-x86

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6614 4407c894-4637-0410-b4f5-ada5f102cad1
Add ARM jump buffer definition

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6615 4407c894-4637-0410-b4f5-ada5f102cad1