re PR sanitizer/81262 (verify_flow_info failed for asmgoto test-case with -fsanitize=undefined)

	PR sanitizer/81262
	* bb-reorder.c (fix_up_fall_thru_edges): Move variable declarations to
	the right scopes, make sure cond_jump isn't preserved between multiple
	iterations.  Search for fallthru edge whenever there are 3+ edges and
	use find_fallthru_edge for it.

From-SVN: r249866

gcc/bb-reorder.c

@@ -1819,7 +1819,6 @@ fix_up_fall_thru_edges (void)
       edge succ2;
       edge fall_thru = NULL;
       edge cond_jump = NULL;
-      rtx_code_label *fall_thru_label;
 
       fall_thru = NULL;
       if (EDGE_COUNT (cur_bb->succs) > 0)