VcsBase: Modernize headers

* Use pragma once
* Use override
* Remove Q_DECLARE_PRIVATE as that makes no sense for QtCreator

Change-Id: Ic31d4868c172a0b8fcb50cc9a71a6e95639cf84c
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/vcsbase/vcsbaseconstants.h

@@ -23,8 +23,7 @@
 **
 ****************************************************************************/
 
-#ifndef VCSBASE_CONSTANTS_H
-#define VCSBASE_CONSTANTS_H
+#pragma once
 
 #include <QtGlobal>
 
@@ -51,5 +50,3 @@ const char VAR_VCS_TOPLEVELPATH[] = "CurrentProject:VcsTopLevelPath";
 
 } // namespace Constants
 } // namespace VcsBase
-
-#endif // VCSBASE_CONSTANTS_H