Since the test goes through all moz.build files disregarding DIRS and
the conditions that may disable directories, in some cases, moz.builds
can fail to be evaluated properly because of missing variables in
config.status. This time (because it's not the first), it's
LLVM_DLLTOOL.
After fixing that, it turns out many of the files/directories pointed to
by Files() directives were removed or moved.
While here, make the test script python3-ready.
Differential Revision: https://phabricator.services.mozilla.com/D70157
--HG--
extra : moz-landing-system : lando
ac5b6e6cd0