[ARM] Allow combination of aprofile and rmprofile multilibs

[ARM] Allow combination of aprofile and rmprofile multilibs

2017-05-05  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/
    * config.gcc: Allow combinations of aprofile and rmprofile values for
    --with-multilib-list.
    * config/arm/t-multilib: New file.
    * config/arm/t-aprofile: Remove initialization of MULTILIB_*
    variables.  Remove setting of ISA and floating-point ABI in
    MULTILIB_OPTIONS and MULTILIB_DIRNAMES.  Set architecture and FPU in
    MULTI_ARCH_OPTS_A and MULTI_ARCH_DIRS_A rather than MULTILIB_OPTIONS
    and MULTILIB_DIRNAMES respectively.  Add comment to introduce all
    matches.  Add architecture matches for marvel-pj4 and generic-armv7-a
    CPU options.
    * config/arm/t-rmprofile: Likewise except for the matches changes.
    * doc/install.texi (--with-multilib-list): Document the combination of
    aprofile and rmprofile values and warn about pitfalls in doing that.

From-SVN: r247646