Fix distcc support and add icecream (mr !585)

(cherry picked from commit cb38e5ac)

3b71d761 Fix distcc support in cmake 37cf49b0 Add support for the icecream distributed compiler

• [2018-02-28 15:28] Validation started with lhcb-gaudi-merge#436
• [2018-03-01 00:32] Validation started with lhcb-2018-patches#131
• [2018-03-01 10:26] Validation started with lhcb-2018-patches#131
• [2018-03-01 15:12] Validation started with lhcb-2018-patches#1
• [2018-03-01 17:21] Validation started with lhcb-2018-patches#132
• [2018-03-02 00:28] Validation started with lhcb-2018-patches#133

approved this merge request

merged

mentioned in commit 6ebc5d99