Remove --check_plt flag passed to dialyzer

Accidently added in 88623b53aa94bd4ce8293b9c5c71f9578e9fc816.

Change-Id: Ic77c4a635bbf8cd2ffce75294aeec499d4c0d041
Reviewed-on: http://review.couchbase.org/25396
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Filipe David Borba Manana <fdmanana@gmail.com>