[calls] call: Prefer pragma once over explicit include guard

[Evangelos Ribeiro Tzaras <devrtz src gnome org>]

commit 3ebc3ed88d1a0d94d471c3aca62fdf012fda32d3
Author: Evangelos Ribeiro Tzaras <devrtz fortysixandtwo eu>
Date:   Fri Feb 4 04:56:49 2022 +0100

    call: Prefer pragma once over explicit include guard

 src/calls-call.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
---
diff --git a/src/calls-call.h b/src/calls-call.h
index cae105f8..1becc3ff 100644
--- a/src/calls-call.h
+++ b/src/calls-call.h
@@ -22,8 +22,7 @@
  *
  */
 
-#ifndef CALLS_CALL_H__
-#define CALLS_CALL_H__
+#pragma once
 
 #include <glib-object.h>
 
@@ -85,4 +84,3 @@ gboolean calls_call_state_parse_nick (CallsCallState  *state,
 
 G_END_DECLS
 
-#endif /* CALLS_CALL_H__ */