re PR rtl-optimization/88018 (ICE in insert_insn_on_edge at cfgrtl.c:1952 since r255066)

	PR rtl-optimization/88018
	* cfgrtl.c (fixup_abnormal_edges): Guard moving insns to fallthru edge
	on the presence of fallthru edge, rather than if it is a USE or not.

	* g++.dg/tsan/pr88018.C: New test.

From-SVN: r266236

gcc/testsuite/g++.dg/tsan/pr88018.C

+// PR rtl-optimization/88018
+// { dg-do compile }
+// { dg-skip-if "" { *-*-* }  { "*" } { "-O0" } }
+// { dg-options "-fsanitize=thread -fno-ipa-pure-const -O1 -fno-inline-functions-called-once -w" }
+
+#include "../pr69667.C"