add a dummy main

Author: HaiwangYu

triton/test/check_triton.cxx

@@ -72,4 +72,13 @@ int main() {
   }
   return 0;
 }
+
+#else
+
+#include <iostream>
+int main() {
+    std::cerr << "This test requires libtorch support. Skipping.\n";
+    return 0;
+}
+
 #endif // HAVE_LIBTORCH

triton/test/test_triton_inference.cxx

@@ -162,4 +162,12 @@ int main() {
     return 0;
 }
 
+#else
+
+#include <iostream>
+int main() {
+    std::cerr << "This test requires libtorch support. Skipping.\n";
+    return 0;
+}
+
 #endif // HAVE_LIBTORCH