t: factor out FUNNYNAMES as shared lazy prereq

t: factor out FUNNYNAMES as shared lazy prereq

A fair number of tests need to check that the filesystem supports file
names including "funny" characters, like newline, tab, and double-quote.
Jonathan Nieder suggested that this be extracted into a lazy prereq in
the top-level `test-lib.sh`. This patch effects that change.

The FUNNYNAMES prereq now uniformly requires support for newlines, tabs,
and double-quotes in filenames. This very slightly decreases the power
of some tests, which might have run previously on a system that supports
(e.g.) newlines and tabs but not double-quotes, but now will not. This
seems to me like an acceptable tradeoff for consistency.

One test (`t/t9902-completion.sh`) defined FUNNYNAMES to further require
the separators \034 through \037, the test for which was implemented
using the Bash-specific $'\034' syntax. I've elected to leave this one
as is, renaming it to FUNNIERNAMES.

After this patch, `git grep 'test_\(set\|lazy\)_prereq.*FUNNYNAMES'` has
only one result.

Signed-off-by: William Chargin <wchargin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>