Issue #19512, #19515: remove shared identifiers, move identifiers where they
are used.

Move also _Py_IDENTIFIER() defintions to the top in modified files to remove
identifiers duplicated in the same file.
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
index a7123b7..ab0fea4 100644
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -17,6 +17,8 @@
 static long nb_threads = 0;
 static PyObject *str_dict;
 
+_Py_IDENTIFIER(stderr);
+
 /* Lock objects */
 
 typedef struct {
@@ -1005,7 +1007,7 @@
             PySys_WriteStderr(
                 "Unhandled exception in thread started by ");
             PyErr_Fetch(&exc, &value, &tb);
-            file = _PySys_GetObjectId(&_PyId_stderr);
+            file = _PySys_GetObjectId(&PyId_stderr);
             if (file != NULL && file != Py_None)
                 PyFile_WriteObject(boot->func, file, 0);
             else