thunk: switch from pragma to classical header guard

Pragma isn't standardized and it didn't seem to be working properly
in a project where simply replacing it with this commit fixed
compilation

1 files changed, 5 insertions, 1 deletions

diff --git a/thunk.h b/thunk.h
index 1ae6463..c388140 100644
--- a/thunk.h
+++ b/thunk.h
@@ -1,3 +1,6 @@
+#ifndef _THUNK_H
+#define _THUNK_H
+
 /*
  *  Machinery for generating simple C thunks using the C preprocessor.
  *  Copyright (C) 2016 Vito Caputo <vcaputo@pengaru.com>
@@ -16,7 +19,6 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#pragma once
 #include <assert.h>
 #include <stdlib.h>
 
@@ -356,3 +358,5 @@ struct thunk_t {
 static inline int thunk_dispatch(thunk_t *thunk) {
 	return thunk->dispatch(thunk);
 }
+
+#endif