[arm][6/X] Add support for __[us]sat16 intrinsics

[arm][6/X] Add support for __[us]sat16 intrinsics

This last patch adds the the __ssat16 and __usat16 intrinsics that perform
"clipping" to a particular bitwidth on packed SIMD values, setting the Q bit
as appropriate.

	* config/arm/arm.md (arm_<simd32_op>): New define_expand.
	(arm_<simd32_op><add_clobber_q_name>_insn): New define_insn.
	* config/arm/arm_acle.h (__ssat16, __usat16): Define.
	* config/arm/arm_acle_builtins.def: Define builtins for the above.
	* config/arm/iterators.md (USSAT16): New int_iterator.
	(simd32_op): Handle UNSPEC_SSAT16, UNSPEC_USAT16.
	(sup): Likewise.
	* config/arm/predicates.md (ssat16_imm): New predicate.
	(usat16_imm): Likewise.
	* config/arm/unspecs.md (UNSPEC_SSAT16, UNSPEC_USAT16): Define.

	* gcc.target/arm/acle/simd32.c: Update test.

From-SVN: r277919