Add support for single register window model on SPARC

Add support for single register window model on SPARC

        2011-06-27  Eric Botcazou  <ebotcazou@adacore.com>
        * sparc-tdep.h (struct sparc_frame_cache): Add frame_offset,
        saved_regs_mask and copied_regs_mask fields.
        (sparc_record_save_insn): New prototype.
        * sparc-tdep.c (sparc_alloc_frame_cache): Initialize the new fields.
        (sparc_record_save_insn): New function.
        (sparc_analyze_prologue): Add head comment.  Recognize store insns
        of call-saved registers.  Use OFFSET consistently.  Recognize flat
        frames and cache their settings.
        (sparc32_skip_prologue): Handle flat frames.
        (sparc_frame_cache): Add frame_offset to the base address.
        (sparc32_frame_cache): Adjust to new frame description.
        (sparc32_frame_prev_register): Likewise.
        * sparc64-tdep.c (sparc64_frame_prev_register): Likewise.
        * sparc-sol2-tdep.c (sparc32_sol2_sigtramp_frame_cache): Likewise.
        * sparc64-sol2-tdep.c (sparc64_sol2_sigtramp_frame_cache): Likewise.
        * sparcnbsd-tdep.c (sparc32nbsd_sigcontext_frame_cache): Force the
        frame by calling sparc_record_save_insn.
        * sparc64nbsd-tdep.c (sparc64nbsd_sigcontext_frame_cache): Likewise.
        * sparcobsd-tdep.c (sparc32obsd_sigtramp_frame_cache): Likewise.
        * sparc64obsd-tdep.c (sparc64obsd_frame_cache): Likewise.