decouple internal.h headers

Saves comitters' daily life by avoid #include-ing everything from
internal.h to make each file do so instead.  This would significantly
speed up incremental builds.

We take the following inclusion order in this changeset:

1.  "ruby/config.h", where _GNU_SOURCE is defined (must be the very
    first thing among everything).
2.  RUBY_EXTCONF_H if any.
3.  Standard C headers, sorted alphabetically.
4.  Other system headers, maybe guarded by #ifdef
5.  Everything else, sorted alphabetically.

Exceptions are those win32-related headers, which tend not be self-
containing (headers have inclusion order dependencies).

1 files changed, 11 insertions, 3 deletions

diff --git a/enumerator.c b/enumerator.c
index 9d0547da05..790818064f 100644
--- a/enumerator.c
+++ b/enumerator.c
@@ -12,14 +12,22 @@
 
 ************************************************/
 
-#include "ruby/ruby.h"
-#include "internal.h"
-#include "id.h"
+#include "ruby/config.h"
 
 #ifdef HAVE_FLOAT_H
 #include <float.h>
 #endif
 
+#include "id.h"
+#include "internal.h"
+#include "internal/enumerator.h"
+#include "internal/error.h"
+#include "internal/hash.h"
+#include "internal/imemo.h"
+#include "internal/numeric.h"
+#include "internal/range.h"
+#include "ruby/ruby.h"
+
 /*
  * Document-class: Enumerator
  *