[AArch64] Tie operand 1 to operand 0 in AESMC pattern when AES/AESMC fusion is enabled

	* config/aarch64/aarch64.c (aarch64_fusion_enabled_p): New function.
	* config/aarch64/aarch64-protos.h (aarch64_fusion_enabled_p): Declare
	prototype.
	* config/aarch64/aarch64-simd.md (aarch64_crypto_aes<aesmc_op>v16qi):
	Add "=w,0" alternative.  Enable it when AES/AESMC fusion is enabled.

From-SVN: r236820