io.c, ruby.c: include internal/variable.h for rb_gvar_readonly_setter

Same as 053f78e13988e9253d1f207bf5e23d9505112b32.
emscripten requires a prototype declaration of rb_gvar_readonly_setter
if it is refered as a function pointer.

1 files changed, 1 insertions, 0 deletions

diff --git a/io.c b/io.c
index a6a7dd3f82..294abfe6b0 100644
--- a/io.c
+++ b/io.c
@@ -127,6 +127,7 @@
 #include "ccan/list/list.h"
 #include "internal/thread.h"
 #include "internal/transcode.h"
+#include "internal/variable.h"
 #include "ruby/io.h"
 #include "ruby/thread.h"
 #include "ruby/util.h"