Add support for ARMv8-R architecture

Add support for ARMv8-R architecture

2017-07-06  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/
    * config/arm/arm-cpus.in (armv8-r): Add new entry.
    * config/arm/arm-isa.h (ISA_ARMv8r): Define macro.
    * config/arm/arm-tables.opt: Regenerate.
    * config/arm/arm.h (enum base_architecture): Add BASE_ARCH_8R
    enumerator.
    * doc/invoke.texi: Mention -march=armv8-r and its extensions.

    gcc/testsuite/
    * lib/target-supports.exp: Generate
    check_effective_target_arm_arch_v8r_ok, add_options_for_arm_arch_v8r
    and check_effective_target_arm_arch_v8r_multilib.

    libgcc/
    * config/arm/lib1funcs.S: Defined __ARM_ARCH__ to 8 for ARMv8-R.

From-SVN: r250025