Modifications to make libgcc compile for arceb-elf32.

2013-02-25  Simon Cook  <simon.cook@embecosm.com>

        * config.host: arc-*-elf* renamed to arc*-*-elf*.
        Added arc*-*-* definition as ARC cpu type.
        * config/arc/arc.h (ASM_SPEC): Change condition for assembler
        arguments.
        (DRIVER_SELF_SPECS): Parse -mA6 and -mA7.