Remove unused declaration

Change-Id: Ifad1444939407ec5187aa6e1c69bdd143f33db46
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/projectexplorer/settingsaccessor.h

@@ -107,8 +107,6 @@ private:
         mutable Utils::PersistentSettingsWriter *m_writer;
     };
 
-    static bool verifyEnvironmentId(const QString &id);
-
     QMap<int, Internal::UserFileVersionHandler *> m_handlers;
     int m_firstVersion;
     int m_lastVersion;