* blockframe.c, frame.h (sigtramp_saved_pc): New routine to fetch

	* blockframe.c, frame.h (sigtramp_saved_pc):  New routine to fetch
	the saved pc from sigcontext on the stack for BSD signal handling.
	* config/i386/tm-i386bsd.h (SIGTRAMP_START, SIGTRAMP_END, FRAME_CHAIN,
	FRAMELESS_FUNCTION_INVOCATION, FRAME_SAVED_PC, SIGCONTEXT_PC_OFFSET):
	Define to make backtracing through sigtramp work.
	* config/vax/tm-vax.h (SIGTRAMP_START, SIGTRAMP_END, TARGET_UPAGES,
	FRAME_SAVED_PC, SIGCONTEXT_PC_OFFSET):  Ditto.