49 Nondeterministic failure building pkg:/shell/bash

This wad sets NO_PARALLEL_MAKE in the bash build script in order to work around a race condition in the bash build process that causes the build to fail nondeterministically on multiprocessor systems.

Testing Done:

Built shell/bash several times on a multiprocessor system. Prior to this change, the build sometimes failed. With this change, the build always succeeded.