Implement support for AArch64 Crypto SHA256.

Implement support for AArch64 Crypto SHA256.

gcc/
	* config/aarch64/aarch64-simd-builtins.def: Update builtins table.
	* config/aarch64/aarch64-simd.md (aarch64_crypto_sha256h<sha256_op>v4si,
	aarch64_crypto_sha256su0v4si, aarch64_crypto_sha256su1v4si): New.
	* config/aarch64/arm_neon.h (vsha256hq_u32, vsha256h2q_u32,
	vsha256su0q_u32, vsha256su1q_u32): New.
	* config/aarch64/iterators.md (UNSPEC_SHA256H<2>, UNSPEC_SHA256SU<01>):
	New.
	(CRYPTO_SHA256): New int iterator.
	(sha256_op): New int attribute.

testsuite/
	* gcc.target/aarch64/sha256_1.c: New.

From-SVN: r206119