Disable -Wliteral-suffix for standard UDLs

Disable -Wliteral-suffix for standard UDLs

	* include/bits/basic_string.h (operator""s): Add pragmas to disable
	-Wliteral-suffix warnings.
	* include/experimental/string_view (operator""sv): Likewise.
	* include/std/chrono (operator""h, operator""min, operator""s)
	(operator""ms, operator""us, operator""ns): Likewise.
	* include/std/complex (operator""if, operator""i, operator""il):
	Likewise.
	* include/std/string_view (operator""sv): Likewise.
	* testsuite/20_util/duration/literals/range.cc: Adjust dg-error.

From-SVN: r255320