Build _ctypes_test as a shared module (fixes #721) (#747)

Author: geofft

cpython-unix/extension-modules.yml

@@ -145,6 +145,7 @@ _ctypes:
     - dl
 
 _ctypes_test:
+  build-mode: shared
   sources:
     - _ctypes/_ctypes_test.c
   links:

src/validation.rs

@@ -649,6 +649,10 @@ const _DEPENDENCY_PACKAGE_SYMBOLS_BUNDLED: &[&str] = &[
     "TkBindInit",
     "TkCreateFrame",
     "Tk_FreeGC",
+    // _ctypes_test module
+    "my_free",
+    "mystrdup",
+    "top",
 ];
 
 const PYTHON_EXPORTED_SYMBOLS: &[&str] = &[
@@ -872,7 +876,7 @@ const GLOBAL_EXTENSIONS_WINDOWS_PRE_3_13: &[&str] = &["_msi"];
 const GLOBAL_EXTENSIONS_WINDOWS_NO_STATIC: &[&str] = &["_testinternalcapi", "_tkinter"];
 
 /// Extension modules that should be built as shared libraries.
-const SHARED_LIBRARY_EXTENSIONS: &[&str] = &["_crypt", "_tkinter"];
+const SHARED_LIBRARY_EXTENSIONS: &[&str] = &["_crypt", "_ctypes_test", "_tkinter"];
 
 const PYTHON_VERIFICATIONS: &str = include_str!("verify_distribution.py");