ClangTool output cleanup

Information messages sent to stdout by ClangTool now only happen when the
-debug flag is set.

Error messages that used to go to stdout now go to stderr.

Author: Ariel J Bernal <ariel.j.bernal@intel.com>


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177177 91177308-0d34-0410-b5e6-96231b3b80d8