Strict failure on missing dependencies, too

Author: tiran

setup.py

@@ -665,7 +665,9 @@ def print_three_column(lst):
                 print("Custom linker flags may require --with-openssl-rpath=auto")
             print()
 
-        if os.environ.get("PYTHONSTRICTEXTENSIONBUILD") and (self.failed or self.failed_on_import):
+        if os.environ.get("PYTHONSTRICTEXTENSIONBUILD") and (
+            self.failed or self.failed_on_import or self.missing
+        ):
             raise RuntimeError("Failed to build some stdlib modules")
 
     def build_extension(self, ext):