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, 9 insertions, 3 deletions

diff --git a/mjit.c b/mjit.c
index 33abfbe3e9..5d1a182b0b 100644
--- a/mjit.c
+++ b/mjit.c
@@ -11,14 +11,20 @@
 
 // To share variables privately, include mjit_worker.c instead of linking.
 
-#include "internal.h"
+#include "ruby/config.h"
 
 #if USE_MJIT
 
-#include "mjit_worker.c"
-
 #include "constant.h"
 #include "id_table.h"
+#include "internal.h"
+#include "internal/class.h"
+#include "internal/file.h"
+#include "internal/hash.h"
+#include "internal/mjit.h"
+#include "internal/warnings.h"
+
+#include "mjit_worker.c"
 
 // Copy ISeq's states so that race condition does not happen on compilation.
 static void