Closes #4547

I missed to check this in with commit
71786c0505926aaf7e9b2477b2fb7ee16a915ec6, which only disabled the test.
This fixes the actual linker error.

Closes https://github.com/curl/curl/pull/3568

- Get rid of variable that was generating false positive warning
(unitialized)

- Fix issues in tests

- Reduce scope of several variables all over

etc

Closes #2631

If configure detects fnmatch to be available, use that instead of our
custom one for FTP wildcard pattern matching. For standard compliance,
to reduce our footprint and to use already well tested and well
exercised code.

A POSIX fnmatch behaves slightly different than the internal function
for a few test patterns currently and the macOS one yet slightly
different. Test case 1307 is adjusted for these differences.

Closes #2626

A non-escaped bracket ([) is for a character group - as documented. It
will *not* match an individual bracket anymore. Test case 1307 updated
accordingly to match.

Problem detected by OSS-Fuzz, although this fix is probably not a final
fix for the notorious timeout issues.

Bug: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=8525
Closes #2614

The previous limit of 5 can still end up in situation that takes a very
long time and consumes a lot of CPU.

If there is still a rare use case for this, a user can provide their own
fnmatch callback for a version that allows a larger set of wildcards.

This commit was triggered by yet another OSS-Fuzz timeout due to this.
Bug: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=8369

Closes #2587

Whenever an expected pattern syntax rule cannot be matched, the
character starting the rule loses its special meaning and the parsing
is resumed:
- backslash at the end of pattern string matches itself.
- Error in [:keyword:] results in set containing :\[dekorwy.

Unit test 1307 updated for this new situation.

Closes #2273

Also be more tolerant about set pattern syntax.
Update unit test 1307 accordingly.

Bug: https://curl.haxx.se/mail/lib-2018-01/0114.html