Change PyUnicode_KIND to 1,2,4. Drop _KIND_SIZE and _CHARACTER_SIZE.
diff --git a/Modules/_sre.c b/Modules/_sre.c
index c685bae..395a120 100644
--- a/Modules/_sre.c
+++ b/Modules/_sre.c
@@ -1669,7 +1669,7 @@
             return NULL;
         ptr = PyUnicode_DATA(string);
         *p_length = PyUnicode_GET_LENGTH(string);
-        *p_charsize = PyUnicode_CHARACTER_SIZE(string);
+        *p_charsize = PyUnicode_KIND(string);
         *p_logical_charsize = 4;
         return ptr;
     }