Clean up range.c. Use mrb_int. Use mrb_vtype.

src/range.c

@@ -16,8 +16,8 @@ static void
 range_check(mrb_state *mrb, mrb_value a, mrb_value b)
 {
   mrb_value ans;
-  int ta;
-  int tb;
+  enum mrb_vtype ta;
+  enum mrb_vtype tb;
 
   ta = mrb_type(a);
   tb = mrb_type(b);
@@ -181,7 +181,7 @@ r_le(mrb_state *mrb, mrb_value a, mrb_value b)
   /* output :a < b => -1, a = b =>  0, a > b => +1 */
 
   if (mrb_type(r) == MRB_TT_FIXNUM) {
-    int c = mrb_fixnum(r);
+    mrb_int c = mrb_fixnum(r);
     if (c == 0 || c == -1) return TRUE;
   }
 
@@ -208,7 +208,7 @@ r_ge(mrb_state *mrb, mrb_value a, mrb_value b)
   /* output :a < b => -1, a = b =>  0, a > b => +1 */
 
   if (mrb_type(r) == MRB_TT_FIXNUM) {
-    int c = mrb_fixnum(r);
+    mrb_int c = mrb_fixnum(r);
     if (c == 0 || c == 1) return TRUE;
   }