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.