This is one small step towards consistency between GeckoView builds
that run through `mozharness` and Android builds, that don't.
This will expose `source-repo.h`, so that `MOZ_SOURCE_*` are found at
Gradle configuration time and address Bug 1976521, where `VCS_HASH`
was empty. But it will also help with tickets like Bug 1564483, which
wants to generate Java code for consumption in `android-components`.
N.b.: at this time, we can't drive this interaction from Gradle,
because the Gradle build does not run the `mach*` tasks for
`MOZILLA_OFFICIAL` builds.
Differential Revision: https://phabricator.services.mozilla.com/D257179
Nick Alexander
c092390d08