py: Change type signature of builtin funs that take variable or kw args.
With this patch the n_args parameter is changed type from mp_uint_t to
size_t.
diff --git a/py/modmath.c b/py/modmath.c
index cffd8cf..6abf8ab 100644
--- a/py/modmath.c
+++ b/py/modmath.c
@@ -152,7 +152,7 @@
// Function that takes a variable number of arguments
// log(x[, base])
-STATIC mp_obj_t mp_math_log(mp_uint_t n_args, const mp_obj_t *args) {
+STATIC mp_obj_t mp_math_log(size_t n_args, const mp_obj_t *args) {
mp_float_t x = mp_obj_get_float(args[0]);
if (x <= (mp_float_t)0.0) {
math_error();