include: Switch to #pragma once pattern

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/core/gsmtap_util.h b/include/osmocom/core/gsmtap_util.h
index eaa32a0..a5c03e7 100644
--- a/include/osmocom/core/gsmtap_util.h
+++ b/include/osmocom/core/gsmtap_util.h
@@ -1,5 +1,4 @@
-#ifndef _GSMTAP_UTIL_H
-#define _GSMTAP_UTIL_H
+#pragma once
 
 #include <stdint.h>
 #include <osmocom/core/write_queue.h>
@@ -55,5 +54,3 @@
 		unsigned int len);
 
 /*! @} */
-
-#endif /* _GSMTAP_UTIL_H */