ensure rustc does not panic by the test for issue-26092

Author: m-ysk

src/test/run-make-fulldeps/issue-26092/Makefile

@@ -1,4 +1,6 @@
 -include ../tools.mk
 
+# This test ensures that rustc does not panic with `-o ""` option.
+
 all:
-	$(RUSTC) -o "" blank.rs 2>&1 | $(CGREP) -i 'No such file or directory'
+	$(RUSTC) -o "" blank.rs 2>&1 | $(CGREP) -i 'panic' && exit 1 || exit 0