writeback for appropriate cores/arch.
* testsuite/gas/arm/ld-sp-warn-cortex-m3.d: New test.
* testsuite/gas/arm/ld-sp-warn-cortex-m3.l: New test.
* testsuite/gas/arm/ld-sp-warn-cortex-m4.d: New test.
* testsuite/gas/arm/ld-sp-warn-cortex-m4.l: New test.
* testsuite/gas/arm/ld-sp-warn-v7.d: New test.
* testsuite/gas/arm/ld-sp-warn-v7.l: New test.
* testsuite/gas/arm/ld-sp-warn-v7a.d: New test.
* testsuite/gas/arm/ld-sp-warn-v7a.l: New test.
* testsuite/gas/arm/ld-sp-warn-v7e-m.l: New test.
* testsuite/gas/arm/ld-sp-warn-v7em.d: New test.
* testsuite/gas/arm/ld-sp-warn-v7m.d: New test.
* testsuite/gas/arm/ld-sp-warn-v7m.l: New test.
* testsuite/gas/arm/ld-sp-warn-v7r.d: New test.
* testsuite/gas/arm/ld-sp-warn-v7r.l: New test.
* testsuite/gas/arm/ld-sp-warn.s: New test.