tests: exercise "git apply" with weird filenames

tests: exercise "git apply" with weird filenames

Check that "git apply" can cope with strange filenames, particularly
filenames with spaces.

Not all platforms have a sane enough diff -u and expand to
reliably create the such patches and maybe future versions of GNU
diff will handle funny characters differently, so this uses
pre-generated patches.  The script used to generate them is in
t/t4135/make-patches.

Filenames with tabs are not usable on NTFS; use something like the
FUNNYNAMES prerequisite from v1.3.0-rc1~67 (2006-03-03) to skip the
relevant tests when appropriate.  The detection is not shared in
test-lib.sh to avoid wasting time while running other test scripts.

Backslash is the path separator on Windows, so do not used it in
file names there (v1.6.3-rc0~93^2~6, 2009-03-13).

Finally, filenames starting with a quotation mark do not behave well
in msys (see v1.7.0-rc0~94^2, t4030, t4031: work around bogus MSYS
bash path conversion, 2010-01-01), so skip those tests on Windows,
too.

Helped-by: Andreas Schwab <schwab@linux-m68k.org>
Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>