Merging r247757:

------------------------------------------------------------------------
r247757 | geek4civic | 2015-09-15 20:10:43 -0400 (Tue, 15 Sep 2015) | 9 lines

llvm/CodeGen/CommandFlags.h: Prune doubleslash in #include.

While packaging 3.7 for Fedora, the debug info splitting
process fell over this, so fix it upstream seems like a good plan.

This should be put in the 3.7 branch as well.

Noticed by Dave Airlie <airlied@redhat.com>

------------------------------------------------------------------------

llvm-svn: 252482