clang ARM 4.9 patches

Greg, Please apply the attached mbox to 4.9. The first patch and last patch had to be adjusted for location, but no real changes. They are to support 32b ARM on 4.9 building with Clang. Here's a run of the mbox building and booting: https://travis-ci.com/ClangBuiltLinux/continuous-integration/builds/93425484 WIP to backport warning fixes.