include: Switch to #pragma once pattern

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/src/gsm/milenage/aes.h b/src/gsm/milenage/aes.h
index ba384a9..7e97f61 100644
--- a/src/gsm/milenage/aes.h
+++ b/src/gsm/milenage/aes.h
@@ -12,8 +12,7 @@
  * See README and COPYING for more details.
  */
 
-#ifndef AES_H
-#define AES_H
+#pragma once
 
 #define AES_BLOCK_SIZE 16
 
@@ -23,5 +22,3 @@
 void * aes_decrypt_init(const u8 *key, size_t len);
 void aes_decrypt(void *ctx, const u8 *crypt, u8 *plain);
 void aes_decrypt_deinit(void *ctx);
-
-#endif /* AES_H */