include: Switch to #pragma once pattern

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/gsm/rxlev_stat.h b/include/osmocom/gsm/rxlev_stat.h
index 415509d..7183b17 100644
--- a/include/osmocom/gsm/rxlev_stat.h
+++ b/include/osmocom/gsm/rxlev_stat.h
@@ -1,5 +1,4 @@
-#ifndef _OSMOCORE_RXLEV_STATS_H
-#define _OSMOCORE_RXLEV_STATS_H
+#pragma once
 
 #define NUM_RXLEVS 32
 #define NUM_ARFCNS 1024
@@ -18,5 +17,3 @@
 void rxlev_stat_reset(struct rxlev_stats *st);
 
 void rxlev_stat_dump(const struct rxlev_stats *st);
-
-#endif /* _OSMOCORE_RXLEV_STATS_H */