Add method for finding XML doc files for systems that don't support GLOB_BRACE.

In particular, Solaris and perhaps others do not support the above mentioned
GNU extension. In this case the paths are simply expanded without the braces
and the calls to glob are made separately.

Note: I could not explain memory allocation failures that were being reported
from within libxml itself when making calls to glob without using GLOB_NOCHECK.
This is the only reason why that flag is being used.

(closes issue #15402)
Reported by: snuffy
Patches: 
      bug_xmlpatt-v3.diff uploaded by snuffy (license 35),
      modified by me


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@278708 65c4cc65-6c06-0410-ace0-fbb531ad65f3