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, 4 deletions

diff --git a/re.c b/re.c
index b15c3a07a8..56b5144f9f 100644
--- a/re.c
+++ b/re.c
@@ -9,13 +9,20 @@
 
 **********************************************************************/
 
+#include "ruby/config.h"
+
+#include <ctype.h>
+
+#include "encindex.h"
+#include "internal.h"
+#include "internal/error.h"
+#include "internal/hash.h"
+#include "internal/imemo.h"
+#include "internal/re.h"
+#include "regint.h"
 #include "ruby/encoding.h"
 #include "ruby/re.h"
 #include "ruby/util.h"
-#include "internal.h"
-#include "regint.h"
-#include "encindex.h"
-#include <ctype.h>
 
 VALUE rb_eRegexpError;