Explicitly check if native access is allowed.

Author: fangerer

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/ImpModuleBuiltins.java

@@ -271,6 +271,10 @@ private Object loadDynamicModuleWithSpec(String name, String path, InteropLibrar
         private void ensureCapiWasLoaded() {
             PythonContext context = getContext();
             if (!context.hasCApiContext()) {
+                if (!context.getEnv().isNativeAccessAllowed()) {
+                    throw raise(ImportError, ErrorMessages.NATIVE_ACCESS_NOT_ALLOWED);
+                }
+
                 Env env = context.getEnv();
                 CompilerDirectives.transferToInterpreterAndInvalidate();