FIXUP: Add timeout option for pool:get()

Consider POOL_EMPTY_SLOT marker when closing a pool.

Author: Totktonada

mysql/init.lua

@@ -185,7 +185,7 @@ local function pool_close(self)
     self.usable = false
     for i = 1, self.size do
         local mysql_conn = self.queue:get()
-        if mysql_conn ~= nil then
+        if mysql_conn ~= POOL_EMPTY_SLOT then
             mysql_conn:close()
         end
     end