include: Switch to #pragma once pattern

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/gprs/protocol/gsm_08_16.h b/include/osmocom/gprs/protocol/gsm_08_16.h
index 4c3eda3..8b2ac56 100644
--- a/include/osmocom/gprs/protocol/gsm_08_16.h
+++ b/include/osmocom/gprs/protocol/gsm_08_16.h
@@ -1,5 +1,4 @@
-#ifndef _OSMO_08_16_H
-#define _OSMO_08_16_H
+#pragma once
 
 /* GPRS Networks Service (NS) messages on the Gb interface
  * 3GPP TS 08.16 version 8.0.1 Release 1999 / ETSI TS 101 299 V8.0.1 (2002-05)
@@ -81,5 +80,3 @@
 	NS_CAUSE_UNKN_IP_ADDR		= 0x13,
 	NS_CAUSE_UNKN_IP_TEST_FAILED	= 0x14,
 };
-
-#endif