gdi32/tests: Make sure to use return value (LLVM/Clang).

dlls/gdi32/tests/path.c

@@ -89,6 +89,7 @@ static void test_widenpath(void)
     Polyline(hdc, pnt, 6);
     EndPath(hdc);
     ret = WidenPath(hdc);
+    ok(ret == TRUE, "WidenPath failed: %d", GetLastError());
     nSize = GetPath(hdc, NULL, NULL, 0);
     ok(nSize > 6, "WidenPath should compute a widdened path with a 1px wide pen. Path length is %d, should be more than 6\n", nSize);