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/class.c b/class.c
index c866d1d727..bc64ff7795 100644
--- a/class.c
+++ b/class.c
@@ -23,12 +23,20 @@
  * \{
  */
 
+#include "ruby/config.h"
+#include <ctype.h>
+
+#include "constant.h"
+#include "id_table.h"
 #include "internal.h"
+#include "internal/class.h"
+#include "internal/error.h"
+#include "internal/eval.h"
+#include "internal/hash.h"
+#include "internal/object.h"
+#include "internal/variable.h"
 #include "ruby/st.h"
-#include "constant.h"
 #include "vm_core.h"
-#include "id_table.h"
-#include <ctype.h>
 
 #define id_attached id__attached__