rational.c: update function prefixes.

To be consistent, functions with `rational_` prefix implements methods,
functions with `rat_` prefix are utility functions.

mrbgems/mruby-rational/src/rational.c

@@ -656,7 +656,7 @@ mrb_int mrb_div_int(mrb_state *, mrb_int, mrb_int);
  * redefine Integer#/
  */
 static mrb_value
-rat_int_div(mrb_state *mrb, mrb_value x)
+rational_int_div(mrb_state *mrb, mrb_value x)
 {
   mrb_value y = mrb_get_arg1(mrb);
   mrb_int a = mrb_integer(x);
@@ -684,7 +684,7 @@ rat_int_div(mrb_state *mrb, mrb_value x)
  */
 
 static mrb_value
-rat_int_quo(mrb_state *mrb, mrb_value x)
+rational_int_quo(mrb_state *mrb, mrb_value x)
 {
   mrb_value y = mrb_get_arg1(mrb);
   mrb_int a = mrb_integer(x);
@@ -732,8 +732,8 @@ void mrb_mruby_rational_gem_init(mrb_state *mrb)
   mrb_define_method(mrb, rat, "quo", rational_div, MRB_ARGS_REQ(1));
   mrb_define_method(mrb, mrb->integer_class, "to_r", fix_to_r, MRB_ARGS_NONE());
 #ifndef MRB_USE_COMPLEX
-  mrb_define_method(mrb, mrb->integer_class, "/", rat_int_div, MRB_ARGS_REQ(1)); /* overrride */
-  mrb_define_method(mrb, mrb->integer_class, "quo", rat_int_quo, MRB_ARGS_REQ(1)); /* overrride */
+  mrb_define_method(mrb, mrb->integer_class, "/", rational_int_div, MRB_ARGS_REQ(1)); /* overrride */
+  mrb_define_method(mrb, mrb->integer_class, "quo", rational_int_quo, MRB_ARGS_REQ(1)); /* overrride */
 #endif
   mrb_define_method(mrb, mrb->kernel_module, "Rational", rational_m, MRB_ARGS_ARG(1,1));
 }