Bug 1112314 - Add a mozconfig for Linux64 code coverage builds, r=ted, DONTBUILD because NPOTB

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extra : rebase_source : 0f63920d2cd8c836775a126cd8ae09c48a2f2452
extra : amend_source : 06d6d829c999b005c6221734ebbf0bfb54d1d4f5