deactivate MESS on Mordor

[meowsbits]

ECBP-1110 specifies MESS's deactivation for ETC, but not Mordor. But Mordor should probably deactivate it too -- thanks @chris-mercer for the flag on this.

We'll just need to settle on a block number and add configuration here: https://github.com/etclabscore/core-geth/blob/master/params/config_mordor.go#L96.
Reference for deactivation on Classic: https://github.com/etclabscore/core-geth/blob/master/params/config_classic.go#L85

[meowsbits]

I just pushed ethereumclassic/ECIPs@a828ae5 to the ECBP1100 PR proposing deactivation for Mordor at 10,400,000, which should be in something like 4 days from now (10400000 - 10374238 =~ 25000 / 6400 blocks / day => ~4 days).

[ziogaschr]

I agree with the suggestion. This means that we have to create a release asap.