Bug 1099430, mozilla-central parts: Eliminate the duplication of the build system in comm-central, r=glandium.

See the revisions a few steps prior for more fine-grained information. This just
needs to be relanded because our automation doesn't like non-ASCII commit
messages.

--HG--
extra : amend_source : 0ee4e0da1ea9ada815abfe989c51030db24aac56