glob: backslash escaping bug

curl didn't properly handle escaping characters in a URL with the use of
backslash. It did an attempt, but that failed as reported in bug
3022551. The described example was using the URL
"http://example.com?{AB,C\,D}".

I've now removed the special-handling of letters following the backslash
and I also removed the bad extra check that triggered this particular
bug.

Bug: http://curl.haxx.se/bug/view.cgi?id=3022551
Reported by: Jon Sargeant

RELEASE-NOTES

@@ -20,6 +20,7 @@ This release includes the following bugfixes:
  o ftp-wildcard: avoid tight loop when used without any pattern
  o multi_socket: re-use of same socket without notifying app
  o ftp wildcard: FTP LIST parser FIX
+ o urlglobbing backslash escaping bug
 
 This release includes the following known bugs:
 
@@ -29,6 +30,7 @@ This release would not have looked like this without help, code, reports and
 advice from friends like these:
 
  Dan Fandrich, Kamil Dudka, Krister Johansen, Pavel Raiskup,
+ Jon Sargeant
 
 
         Thanks! (and sorry if I forgot to mention someone)