c-decl.c (grokdeclarator): Move warning for qualified void return types with -pedantic to when...

	* c-decl.c (grokdeclarator): Move warning for qualified void
	return types with -pedantic to when the function type is
	constructed.  At -W, warn in general for qualified function return
	types, except for volatile void.
	* invoke.texi: Document this new warning at -W.

testsuite:
	* gcc.dg/qual-return-1.c, gcc.dg/qual-return-2.c: New tests.

From-SVN: r37056