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, 7 insertions, 3 deletions

diff --git a/ast.c b/ast.c
index 1133fb8a10..3f7061a7b0 100644
--- a/ast.c
+++ b/ast.c
@@ -1,11 +1,15 @@
 /* indent-tabs-mode: nil */
+#include "internal.h"
+#include "internal/parse.h"
+#include "internal/symbol.h"
+#include "internal/warnings.h"
+#include "iseq.h"
+#include "node.h"
 #include "ruby.h"
 #include "ruby/encoding.h"
 #include "ruby/util.h"
-#include "internal.h"
-#include "node.h"
 #include "vm_core.h"
-#include "iseq.h"
+
 #include "builtin.h"
 
 static VALUE rb_mAST;