remove a pch include

Author: dwight

db/commands/distinct.cpp

@@ -15,7 +15,7 @@
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include "pch.h"
+//#include "pch.h"
 #include "../commands.h"
 #include "../instance.h"
 #include "../queryoptimizer.h"