The install-pgbouncer script is not currently reporting any build errors
to the caller, except if the final `rm -rf` fails. Fix the issue by
executing `set -xeuo pipefail` to properly report errors of any
unchecked commands and chaining commands with `&&`'s. While the latter
shouldn't be necessary anymore because of changed options, it's easy
enough to do for this script.
With this change, we now properly notice that building pgbouncer fails
currently because of a missing libevent dependency. This failure is
fixed in a subsequent commit.