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, 19 insertions, 8 deletions

diff --git a/variable.c b/variable.c
index 42c4cb7cd4..46f7dea725 100644
--- a/variable.c
+++ b/variable.c
@@ -11,19 +11,30 @@
 
 **********************************************************************/
 
-#include "ruby/encoding.h"
-#include "ruby/st.h"
-#include "ruby/util.h"
-#include "internal.h"
-#include "id_table.h"
+#include "ruby/config.h"
+#include <stddef.h>
 #include "constant.h"
+#include "debug_counter.h"
 #include "id.h"
-#include "ccan/list/list.h"
 #include "id_table.h"
-#include "debug_counter.h"
-#include "vm_core.h"
+#include "internal.h"
+#include "internal/class.h"
+#include "internal/compilers.h"
+#include "internal/error.h"
+#include "internal/eval.h"
+#include "internal/hash.h"
+#include "internal/re.h"
+#include "internal/symbol.h"
+#include "internal/stdbool.h"
+#include "ccan/list/list.h"
+#include "internal/thread.h"
+#include "internal/variable.h"
+#include "ruby/encoding.h"
+#include "ruby/st.h"
+#include "ruby/util.h"
 #include "transient_heap.h"
 #include "variable.h"
+#include "vm_core.h"
 
 static struct rb_id_table *rb_global_tbl;
 static ID autoload, classpath, tmp_classpath;