include: Switch to #pragma once pattern

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/gsm/lapd_core.h b/include/osmocom/gsm/lapd_core.h
index f88fb11..42ef417 100644
--- a/include/osmocom/gsm/lapd_core.h
+++ b/include/osmocom/gsm/lapd_core.h
@@ -1,5 +1,4 @@
-#ifndef _OSMOCOM_LAPD_H
-#define _OSMOCOM_LAPD_H
+#pragma once
 
 #include <stdint.h>
 
@@ -170,5 +169,3 @@
 int lapd_recv_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx);
 
 /*! @} */
-
-#endif /* _OSMOCOM_LAPD_H */