run-make-check.sh: ccache goodness for everyone

run-make-check.sh: ccache goodness for everyone

Since run-make-check.sh already ensures that ccache is installed,
it makes sense to let everyone benefit from the ccache
tweaks introduced by 4cb5a590537a9caaf61db42ce8ea123d2ab961f3

Note 1: The previous solution using "date" would cause build tools to reset
their timestamps after 24 hours, on subsequent runs of run-make-check.sh.
In order to maximize ccache effectiveness, this commit sets SOURCE_DATE_EPOCH
to a fixed value: the number of seconds elapsed since the Unix epoch as at
January 1, 2000 (chosen to commemorate Y2K armageddon).

Note 2: this commit introduces "set -e". This was actually in effect
before, via "source install-deps.sh". Better to make it explicit.

Fixes: http://tracker.ceph.com/issues/24777
Signed-off-by: Nathan Cutler <ncutler@suse.com>