* c-c++-common/raw-string-3.c: Add comments to checks for multiple
	messages reported for for one line of source code.
	* c-c++-common/raw-string-5.c: Likewise.
	* c-c++-common/raw-string-4.c: Likewise.
	* c-c++-common/raw-string-6.c: Likewise.
	* c-c++-common/pr20000.c: Likewise.

From-SVN: r188477