py/qstr: Use size_t instead of mp_uint_t when counting allocated bytes.
diff --git a/py/mpstate.h b/py/mpstate.h
index c7604e0..012b0ef 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -138,8 +138,8 @@
     // pointer and sizes to store interned string data
     // (qstr_last_chunk can be root pointer but is also stored in qstr pool)
     byte *qstr_last_chunk;
-    mp_uint_t qstr_last_alloc;
-    mp_uint_t qstr_last_used;
+    size_t qstr_last_alloc;
+    size_t qstr_last_used;
 
     // Stack top at the start of program
     // Note: this entry is used to locate the end of the root pointer section.