Redmine#2242: support ** wildcards in findfiles()
Merge pull request #1368 from tzz/feature/2242-findfiles-more-wildcards

Redmine#2242: support ** wildcards in findfiles()
Nuke the unneeded linux conditional
getfields example: remove gid from comparison

On HPUX the field will return 3, not 0 as on Linux or FreeBSD, and since
gid is not essential, just remove it here
lsdir example: improve on the assumptions of what's in /etc

Assumption that /etc/shadow exists is some *ism, as it doesn't exist on
either FreeBSD or HPUX. Replace with the group file, which should be
friendlier, and also ensures that the example illustrates sorting.
strftime example: replace %F with %Y-%m-%d to pet HPUX
Amend per discussion (character classes)
Remove test suppression on win

The test works fine after insert_lines changes (issue #4733)
sort.cf regressed on Win — issue #5107
strftime() does not populate the temp file — issue #5110
insert_lines test regressed — see issue #5120