This can give up to 2x speedup on many AArch64 implementations. Also model
the crypto instructions on Cortex-A57 according to the Optimization Guide.

    gcc/
        * config/aarch64/aarch64.c (cortexa53_tunings): Enable AES fusion.
        (cortexa57_tunings): Likewise.
        (cortexa72_tunings): Likewise.
        (arch_macro_fusion_pair_p): Add support for AES fusion.
        * config/aarch64/aarch64-fusion-pairs.def: Add AES_AESMC entry.
        * config/arm/aarch-common.c (aarch_crypto_can_dual_issue):
        Allow virtual registers before reload so early scheduling works.
        * config/arm/cortex-a57.md (cortex_a57_crypto_simple): Use
        correct latency and pipeline.
        (cortex_a57_crypto_complex): Likewise.
        (cortex_a57_crypto_xor): Likewise.
        (define_bypass): Add AES bypass.

From-SVN: r233268