Commit a no-op change to StringRef to (hopefully) trigger build bots.
r187874 seems to have been missed by the build bot infrastructure, and
the subsequent commits to compiler-rt don't seem to be queuing up new
build requsets. Hopefully this will.

As it happens, having the space here is the more common formatting. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187879 91177308-0d34-0410-b5e6-96231b3b80d8