Make GenericAlias_Type and Generic_Type static. (GH-8076)

(cherry picked from commit 97ae32c92ecc7b3c29f8829a2b79f0f8f8bbf2cc)

Co-authored-by: Benjamin Peterson <benjamin@python.org>
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 4166015..174b767 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -5200,7 +5200,7 @@
     {NULL}  /* sentinel */
 };
 
-PyTypeObject GenericAlias_Type = {
+static PyTypeObject GenericAlias_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "GenericAlias",
     sizeof(PyGenericAliasObject),
@@ -5237,7 +5237,7 @@
     {NULL}  /* sentinel */
 };
 
-PyTypeObject Generic_Type = {
+static PyTypeObject Generic_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "Generic",
     sizeof(PyGenericObject),