re PR ada/41912 (FAIL: gnat.dg/null_pointer_deref1.adb execution test)

	PR ada/41912
	* pa/linux-unwind.h (pa32_fallback_frame_state): Set fs->signal_frame
	for signal frames.
	* pa/hpux-unwind.h (pa32_fallback_frame_state): Likewise.

From-SVN: r155013