fix libcxx test

Author: kish1n

libcxx/utils/libcxx/test/features.py

@@ -336,13 +336,20 @@ def _mingwSupportsModules(cfg):
         or platform.system().lower().startswith("aix")
         # Avoid building on platforms that don't support modules properly.
         or not hasCompileFlag(cfg, "-Wno-reserved-module-identifier")
-        or not sourceBuilds(
+        # older versions don't support extern "C++", newer versions don't support main in named module.
+        or not (sourceBuilds(
             cfg,
             """
             export module test;
             extern "C++" int main(int, char**) { return 0; }
           """,
-        ),
+        ) or sourceBuilds(
+            cfg,
+            """
+            export module test;
+            int main(int, char**) { return 0; }
+          """,
+        )),
     ),
     # The time zone validation tests compare the output of zdump against the
     # output generated by <chrono>'s time zone support.