cd depends
Edit `packages/native_ccache.mk`, add the line:
echo "BUILDING WITH -j$(JOBS)" && \
before the line:
$(MAKE) -j$(JOBS)
make V=1
Check in the output that `make` is invoked with the appropriated `-jX`
option(for the `ccache` package).
make V=1 JOBS=2
Check in the output that `make` is invoked with the appropriated `-j2`
option (for the `ccache` package).
make V=1 build-all
Check in the output that the `JOBS` is propagated to the `ccache` package of all the targets.
Run the Gitian builds and check the output is still deterministic (clear
the cached packages before building).