The main function for epilogue RTL generation, used by expand epilogue

The main function for epilogue RTL generation, used by expand epilogue
patterns.

gcc/

2012-06-18  Ian Bolton  <ian.bolton@arm.com>
            Sameera Deshpande  <sameera.deshpande@arm.com>
            Greta Yorsh  <greta.yorsh@arm.com>

        * config/arm/arm-protos.h (arm_expand_epilogue): New declaration.
        * config/arm/arm.c (arm_expand_epilogue): New function.
        * config/arm/arm.md (epilogue): Update condition and code.
        (sibcall_epilogue): Likewise.

Co-Authored-By: Greta Yorsh <greta.yorsh@arm.com>
Co-Authored-By: Sameera Deshpande <sameera.deshpande@arm.com>
From-SVN: r188742