PR c++/79791
	* typeck.c (string_conv_p): In C++11, always call pedwarn with
	OPT_Wwrite_strings.

	* g++.dg/warn/Wwrite-strings-1.C: New test.
	* g++.dg/warn/Wwrite-strings-2.C: New test.
	* g++.dg/warn/Wwrite-strings-3.C: New test.
	* g++.dg/warn/Wwrite-strings-4.C: New test.
	* g++.dg/warn/Wwrite-strings-5.C: New test.
	* g++.dg/warn/Wwrite-strings-6.C: New test.
	* g++.dg/warn/Wwrite-strings-7.C: New test.
	* g++.dg/warn/Wwrite-strings-8.C: New test.
	* g++.dg/warn/Wwrite-strings-9.C: New test.
	* g++.dg/warn/Wwrite-strings-10.C: New test.
	* g++.dg/warn/Wwrite-strings-11.C: New test.
	* g++.dg/warn/Wwrite-strings-12.C: New test.

From-SVN: r245864