[BOLT] Getting open-source ready

Summary:
BOLT sources are being moved under tools/llvm-bolt/src
and tools/llvm-bolt will contain more files such as LICENSE.txt,
README.txt, etc.

Remove trailing white spaces from our sources.

Create llvm.patch by running

  > git diff f137ed238db11440f03083b1c88b7ffc0f4af65e include lib > \
    tools/llvm-bolt/llvm.patch

README.txt has instructions on checking out sources and applying the
patch.

(cherry picked from FBD7878380)