fixes for '49 Nondeterministic failure building pkg:/shell/bash' and '50 nslookup binary missing from network/dns/bind'

These commits (a) disable parallelism when building shell/bash to work around a race condition in the bash build process on multiprocessor systems and (b) prevent the nslookup(1) binary and man page from being dropped when generating the network/dns/bind IPS package.

Testing Done:

- Built shell/bash several times on a multiprocessor system. Before this change, the build sometimes failed. After this change, the build always succeeds.
- Built network/dns/bind. Verified that the nslookup(1) binary and man page were included in the package. Installed the package, ran nslookup successfully, and viewed its man page.