optabs.c (emit_libcall_block): Add a REG_EH_REGION reg note to all calls within a libcall block to indicate no...

	* optabs.c (emit_libcall_block): Add a REG_EH_REGION reg note to all
	calls within a libcall block to indicate no throws are possible.
	* flow.c (find_basic_blocks, find_basic_blocks_1): Don't look for
	libcall blocks. Don't add edges to exception handlers if we see
	a REG_EH_REGION note with a value of 0.
	(make_edges): Override active_eh_region vector if the call has a note
	indicating the call does not throw.

From-SVN: r24757