On systems with lots of RAM (e.g. 24GB) /proc/sys/fs/file-max divided
by two can exceed the per-process file limit of 2^20. This patch
ensures the value is capped.

(Patch cleaned up by me.)

ASTERISK-24011 #close
Reported by: Michael Myles
Patches:
  safe_asterisk-ulimit.diff uploaded by Michael Myles (License #6626)
........

Merged revisions 424875 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@424878 65c4cc65-6c06-0410-ace0-fbb531ad65f3