1) Teach it to handle files with #include on the first line -- these do
   actually exist in LLVM.
2) Support llvm-c and clang-c include projects.
3) Nuke some stail imports.
4) Switch to using os.path to split the file extension off.
5) Remove debugging leftovers.
6) Add docstring (a really puny one) for the sort function.

I'm continuing te avoid stripping the whitespace on the RHS to preserve
whatever newline characters happen to be in the original file.

llvm-svn: 169222

Kind of important when prepping the include/... tree version of the sort
changes.

llvm-svn: 169132

standards.

I am a terrible Python programmer. Patches more the welcome. Please tell
me how this should look if it should look differently. It's just a tiny
little script so it didn't make sense to go through pre-commit review,
especially as someone who actually knows python may want to just rip it
apart and do it The Right Way.

I will be preparing a commit shortly that uses this script to
canonicalize *all* of the #include lines in LLVM. Really, all of them.

llvm-svn: 169125