With -std=c++NN -pedantic -Wsystem-headers there are warnings about the
use of __int128, which can be suppressed using diagnostic pragmas.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>

libstdc++-v3/ChangeLog:

	* include/bits/cpp_type_traits.h: Add diagnostic pragmas around
	uses of non-standard integer types.
	* include/bits/functional_hash.h: Likewise.
	* include/bits/iterator_concepts.h: Likewise.
	* include/bits/max_size_type.h: Likewise.
	* include/bits/std_abs.h: Likewise.
	* include/bits/stl_algobase.h: Likewise.
	* include/bits/uniform_int_dist.h: Likewise.
	* include/ext/numeric_traits.h: Likewise.
	* include/std/type_traits: Likewise.

Tested powerpc64le-linux. Committed to trunk.