lib/fuzzing: Remove oss-fuzz build.sh stub from the Samba repo

lib/fuzzing: Remove oss-fuzz build.sh stub from the Samba repo

We need to ship the stub build.sh in the oss-fuzz repo, not ours.
This is because otherwise the travis CI checks skip the build
(it thinks we are not set up yet, or have been disabled).

See https://github.com/google/oss-fuzz/pull/3094 for the PR
creating a similar file there.  This is very similar to how
janus-gateway operates, so this is an accepted pattern.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>