Add a catch-all else case so any unanticipated configs pass this test.

GitOrigin-RevId: 3eef58991b26feb37aaae92d5b568b27fab84584
diff --git a/test/frameheadercache_test.pass.cpp b/test/frameheadercache_test.pass.cpp
index ac75f7d..df0f926 100644
--- a/test/frameheadercache_test.pass.cpp
+++ b/test/frameheadercache_test.pass.cpp
@@ -79,4 +79,6 @@
     abort();
   return 0;
 }
+#else
+int main() { return 0; }
 #endif