Tweak include order in yjit_core.c

This is playing it safe. Ruby headers rely on some macros generated by
autoconf that affect what system headers behave. We should take care to
bring in those configs before including systme headers to stay
consistent with the rest of Ruby.

yjit_core.c

@@ -1,10 +1,13 @@
+#include "ruby/ruby.h"
+#include "internal.h"
+#include "vm_sync.h"
+#include "builtin.h"
+
 #include "yjit_asm.h"
 #include "yjit_utils.h"
 #include "yjit_iface.h"
 #include "yjit_core.h"
 #include "yjit_codegen.h"
-#include "vm_sync.h"
-#include "builtin.h"
 
 // Maximum number of versions per block
 #define MAX_VERSIONS 4