This allows to use True and False as values given to
set_config/set_define in moz.configure files, while postponing having to
deal with the long tail of things depending on the values from substs
and defines.
Ideally, everything would handle the bools just fine, but there are too
many things involved to deal with this right now: scripts using
buildconfig.{substs,defines}, scripts using ConfigEnvironment (e.g.
process_define_files.py), ConfigEnvironment itself, etc.
Now that MOZ_BUILD_APP is set to js when building js/src, we can
distinguish those builds with MOZ_BUILD_APP==js instead of BUILDING_JS.
Consequently, remove BUILDING_JS.
Now that MOZ_BUILD_APP is set to js when building js/src, we can
distinguish those builds with MOZ_BUILD_APP==js instead of BUILDING_JS.
Consequently, remove BUILDING_JS.
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.
