[PATCH] add gdbarch_in_function_epilogue_p hook for sparc64

[Jose E. Marchesi]

    > From: jose.marchesi@oracle.com (Jose E. Marchesi)
    > Date: Mon, 10 Feb 2014 13:40:23 +0100
    > 
    > 2013-10-16  Jose E. Marchesi  <jose.marchesi@oracle.com>
    > 
    > 	* sparc-tdep.c (sparc_in_function_epilogue_p): New function.
    > 	(X_RETTURN): New macro.
    > 	* sparc-tdep.h: sparc_in_function_epilogue_p prototype.
    > 
    > 	* sparc64-tdep.c (sparc64_init_abi): Hook
    > 	sparc_in_function_epilogue_p.
    
    Finally managed to test this on OpenBSD/sparc64.  Seems to fix an
    XFAIL and a FAIL in mi-watch.exp for me.  Although those are a bit
    suspect since (software) watchpoints are currently a bit broken on
    OpenBSD/sparc64.  Pretty sure this doesn't cause any regressions
    though, so please go ahaed.

Committed.  Thanks.