make: config -- Drop redundant comma in try-cc call

It takes only two arguments. Note it's not error since
we don't even reference to a third argument here but
just to be consistent and clear.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Ruslan Kuprieiv <kupruser@gmail.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>