testsuite: Add testcase for already fixed PR [PR94686]

This has been fixed by the PR71311 r7-1170-g4618c453
change.

2020-04-21  Jakub Jelinek  <jakub@redhat.com>

	PR c/94686
	* gcc.c-torture/compile/pr94686.c: New test.

gcc/testsuite/ChangeLog

+2020-04-21  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/94686
+	* gcc.c-torture/compile/pr94686.c: New test.
+
 2020-04-21  Iain Sandoe  <iain@sandoe.co.uk>
 
 	PR c++/94661

gcc/testsuite/gcc.c-torture/compile/pr94686.c

+/* PR c/94686 */
+
+int a = 0, b = 0;
+
+int
+foo (void)
+{
+  return (int) (long) (b * 0 >= a & b * 0 >= a);
+}