[arm-embedded] Back port to 4.7 embedded branch to use single mul instruciton for Os

[Terry Guo]

Hi,

I just did this trunk back port to enable 4.7 embedded branch to use single
multiply instruction when optimize for size. Without this back port, current
4.7 embedded branch will use a group instructions to replace single multiply
instruction.

BR,
Terry

gcc/

2013-08-28  Terry Guo  <terry....@arm.com>

        Backport from mainline r201237
        2013-07-24  Terry Guo  <terry....@arm.com>

        * config/arm/arm.c (thumb1_size_rtx_costs): Assign proper cost for
        shift_add/shift_sub0/shift_sub1 RTXs.


gcc/testsuite/

2013-08-28  Terry Guo  <terry....@arm.com>

                Backport from mainline r201237
                2013-07-24  Terry Guo  <terry....@arm.com>

                * gcc.target/arm/thumb1-Os-mult.c: New test case.