Add support for ARM Cortex-M23 processor

Add support for ARM Cortex-M23 processor

2016-11-04  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/
    * config/arm/arm-arches.def (armv8-m.base): Set Cortex-M23 as
    representative core for this architecture.
    * config/arm/arm-cores.def (cortex-m23): Define new processor.
    * config/arm/arm-tables.opt: Regenerate.
    * config/arm/arm-tune.md: Likewise.
    * config/arm/arm.c (arm_v6m_tune): Add Cortex-M23 to the list of cores
    this tuning parameters apply to in the comment.
    * config/arm/bpabi.h (BE8_LINK_SPEC): Add Cortex-M23 to the list of
    valid -mcpu options.
    * doc/invoke.texi (ARM Options): Document new Cortex-M23 processor.

From-SVN: r241848