Add _M_ARM and _ARM_ define

git-svn-id: https://mingw-w64.svn.sourceforge.net/svnroot/mingw-w64/trunk@5629 4407c894-4637-0410-b4f5-ada5f102cad1
Add some ARM specific code paths, cleanup a bit stralign.h, and add missing language & sublanguage defines

git-svn-id: https://mingw-w64.svn.sourceforge.net/svnroot/mingw-w64/trunk@5630 4407c894-4637-0410-b4f5-ada5f102cad1