Wholesale conversion to #pragma once

Kudos to cgmb and https://github.com/cgmb/guardonce

Change-Id: Ifa8970734b8d43fd08c9260c645bdb0228633791
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/libs/ssh/sshconnectionmanager.h

@@ -23,8 +23,7 @@
 **
 ****************************************************************************/
 
-#ifndef SSHCONNECTIONMANAGER_H
-#define SSHCONNECTIONMANAGER_H
+#pragma once
 
 #include "ssh_global.h"
 
@@ -40,5 +39,3 @@ QSSH_EXPORT void releaseConnection(SshConnection *connection);
 QSSH_EXPORT void forceNewConnection(const SshConnectionParameters &sshParams);
 
 } // namespace QSsh
-
-#endif // SSHCONNECTIONMANAGER_H