Fix unquoted spaces in args in clang --verbose output
The behaviour of not quoting spaces appears to have been introduced by
mistake in r190620.
Patch by Brad Moody!
Differential revision: https://reviews.llvm.org/D60997
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@359077 91177308-0d34-0410-b5e6-96231b3b80d8