Merge pull request #1839 from cubicdaiya/issues/comment_include_guard

Add comments at end of include guard

src/gc.c

@@ -1589,5 +1589,5 @@ gc_test(mrb_state *mrb, mrb_value self)
   test_incremental_sweep_phase();
   return mrb_nil_value();
 }
-#endif
-#endif
+#endif  /* GC_DEBUG */
+#endif  /* GC_TEST */

src/mrb_throw.h

@@ -38,4 +38,4 @@ struct mrb_jmpbuf {
 #endif
 };
 
-#endif
+#endif  /* MRB_THROW_H */

src/re.h

@@ -9,4 +9,4 @@
 
 #define REGEXP_CLASS          "Regexp"
 
-#endif
+#endif  /* RE_H */