bpo-36710: Use tstate in pylifecycle.c (GH-14249)

In pylifecycle.c: pass tstate argument, rather than interp argument,
to functions.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 6ec4127..4f83625 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -15792,8 +15792,10 @@
 
 
 PyStatus
-_PyUnicode_InitEncodings(PyInterpreterState *interp)
+_PyUnicode_InitEncodings(PyThreadState *tstate)
 {
+    PyInterpreterState *interp = tstate->interp;
+
     PyStatus status = init_fs_encoding(interp);
     if (_PyStatus_EXCEPTION(status)) {
         return status;