[Mips] Teach llvm-readobj to print MIPS-specific ELF program headers.

The patch reviewed by Michael Spencer.
http://llvm-reviews.chandlerc.com/D1846

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192093 91177308-0d34-0410-b5e6-96231b3b80d8
Windows: Be more explicit with Win32 APIs

This addresses several issues in a similar vein:
 - Use the Unicode APIs when possible, running nm on clang shows that we
   only use Unicode APIs except for FormatMessage, CreateSemaphore, and
   GetModuleHandle.  AFAICT, the latter two are coming from MinGW and
   not LLVM itself.
 - Make getMainExecutable more resilient.  It previously considered
   return values of zero from ::GetModuleFileNameA to be acceptable.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192096 91177308-0d34-0410-b5e6-96231b3b80d8