tests: redo patch for non-GNU gzip installed in /usr/local/bin

tests: redo patch for non-GNU gzip installed in /usr/local/bin

Problem with previous patch reported by Antonio Diaz Diaz in
<http://lists.gnu.org/archive/html/bug-gzip/2013-04/msg00011.html>.
* tests/help-version (gunzip_setuphelp, gzexe_setuphelp)
(zcat_setuphelp, zcmp_setuphelp, zdiff_setuphelp)
(zegrep_setuphelp, zfgrep_setuphelp, zforce_setuphelp)
(zgrep_setuphelp, zless_setuphelp, zmore_setuphelp)
(znew_setuphelp): New functions, used when testing even --help.
(zdiff_setup, zcat_setup, znew_setup, zgrep_setup, gzexe_setup):
Use gzip_setuphelp to set --__bindir.