Merge branch 'wc/make-funnynames-shared-lazy-prereq'

A test prerequisite defined by various test scripts with slightly
different semantics has been consolidated into a single copy and
made into a lazily defined one.

* wc/make-funnynames-shared-lazy-prereq:
t: factor out FUNNYNAMES as shared lazy prereq

diff --cc t/t9902-completion.sh
Simple merge

diff --cc t/t9903-bash-prompt.sh
Simple merge

diff --cc t/test-lib.sh
Simple merge