[ARM] Add initial support for Cortex-A73

[ARM] Add initial support for Cortex-A73

        * config/arm/arm.c (arm_cortex_a73_tune): New struct.
        * config/arm/arm-cores.def (cortex-a73): New entry.
        (cortex-a73.cortex-a35): Likewise.
        (cortex-a73.cortex-a53): Likewise.
        * config/arm/arm-tables.opt: Regenerate.
        * config/arm/arm-tune.md: Likewise.
        * config/arm/bpabi.h (BE8_LINK_SPEC): Handle mcpu=cortex-a73,
        mcpu=cortex-a73.cortex-a35 and mcpu=cortex-a73.cortex-a53.
        * config/arm/t-aprofile: Handle mcpu=cortex-a73,
        mcpu=cortex-a73.cortex-a35 and mcpu=cortex-a73.cortex-a53.
        * doc/invoke.texi (ARM Options): Document cortex-a73,
        cortex-a73.cortex-a35 and cortex-a73.cortex-a53.

From-SVN: r237681