asan: Fix up address sanitizer instrumentation of __builtin_alloca* if it can throw [PR104449]

With -fstack-check* __builtin_alloca* can throw and the asan
instrumentation of this builtin wasn't prepared for that case.
The following patch fixes that by replacing the builtin with the
replacement builtin and emitting any further insns on the fallthru
edge.

I haven't touched the hwasan code which most likely suffers from the
same problem.

2022-02-12  Jakub Jelinek  <jakub@redhat.com>

	PR sanitizer/104449
	* asan.cc: Include tree-eh.h.
	(handle_builtin_alloca): Handle the case when __builtin_alloca or
	__builtin_alloca_with_align can throw.

	* gcc.dg/asan/pr104449.c: New test.
	* g++.dg/asan/pr104449.C: New test.