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, 2 insertions, 0 deletions

diff --git a/iseq.h b/iseq.h
index 25c62a384f..8354a0490f 100644
--- a/iseq.h
+++ b/iseq.h
@@ -11,6 +11,8 @@
 
 #ifndef RUBY_ISEQ_H
 #define RUBY_ISEQ_H 1
+#include "internal/gc.h"
+#include "vm_core.h"
 
 RUBY_EXTERN const int ruby_api_version[];
 #define ISEQ_MAJOR_VERSION ((unsigned int)ruby_api_version[0])