This moves all the reading mozconfig, finding autoconf, refreshing the
old configure, and running the old configure into sandboxed
moz.configure. This effectively bootstraps the sandboxed python configure.
The nice side effect is that now we can have actual dicts for defines
and substs from the start, which simplifies so things, although it
requires adjustments to some unit tests.
At the same time, remove the (useless and wrong) check for AUTOCONF in
old-configure.in (wrong because it very likely is picking autoconf > 2.5).
--HG--
extra : rebase_source : 4a17c9d92c9561ef221b1a300e0e6d48ca56862f