signal_handler_caller.
* tm-68k.h (FRAME_{CHAIN,SAVED_PC}): Deal with sigtramp.
* tm-hp300bsd.h: Define SIGTRAMP_{START,END} not IN_SIGTRAMP.
* inferior.h (IN_SIGTRAMP): Definition moved from infrun.c.
Use SIGTRAMP_START if defined.
* infcmd.c (step_1): Use SIGTRAMP_{START,END} if needed.
* infrun.c (wait_for_inferior): Check IN_SIGTRAMP before SKIP_PROLOGUE.