[gnome-control-center] power: Replace ifdefs with #pragma once

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 27a64cd04bb4ac1421192a41dec965651e64a97b
Author: Robert Ancell <robert ancell canonical com>
Date:   Wed May 30 11:40:53 2018 +1200

    power: Replace ifdefs with #pragma once

 panels/power/cc-power-panel.h | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)
---
diff --git a/panels/power/cc-power-panel.h b/panels/power/cc-power-panel.h
index 4ea08a28c..e8b922dcf 100644
--- a/panels/power/cc-power-panel.h
+++ b/panels/power/cc-power-panel.h
@@ -17,9 +17,7 @@
  *
  */
 
-
-#ifndef _CC_POWER_PANEL_H
-#define _CC_POWER_PANEL_H
+#pragma once
 
 #include <shell/cc-panel.h>
 
@@ -29,5 +27,3 @@ G_BEGIN_DECLS
 G_DECLARE_FINAL_TYPE (CcPowerPanel, cc_power_panel, CC, POWER_PANEL, CcPanel)
 
 G_END_DECLS
-
-#endif /* _CC_POWER_PANEL_H */