fix erroneous disposeOnce calls.

Change-Id: I4ce39e6d6534d1481f7e6b759d61040606da839c

mysqlc/source/mysqlc_connection.cxx

@@ -531,7 +531,7 @@ void SAL_CALL OConnection::close()
         MutexGuard aGuard(m_aMutex);
         checkDisposed(OConnection_BASE::rBHelper.bDisposed);
     }
-    disposeOnce();
+    dispose();
 }
 
 // XWarningsSupplier

mysqlc/source/mysqlc_resultset.cxx

@@ -615,7 +615,7 @@ void SAL_CALL OResultSet::close() throw(SQLException, RuntimeException, std::exc
         mysqlc_sdbc_driver::translateAndThrow(e, *this, m_encoding);
     }
 
-    disposeOnce();
+    dispose();
 }
 
 sal_Bool SAL_CALL OResultSet::first() throw(SQLException, RuntimeException, std::exception)

mysqlc/source/mysqlc_statement.cxx

@@ -138,7 +138,7 @@ void SAL_CALL OCommonStatement::close()
         MutexGuard aGuard(m_aMutex);
         checkDisposed(rBHelper.bDisposed);
     }
-    disposeOnce();
+    dispose();
 }
 
 void SAL_CALL OStatement::clearBatch()