uri: Quiet warning about type qualifiers ignored on function return type

This patch fixes gcc warnings that occur due to the type qualifier 'const'
being ignored on a return type of int.

ASTERISK-24246 #close
Reported by: Shaun Ruffell
patches:
  0001-main-uri-Quiet-warning-about-ignored-attribute-on-re.patch uploaded by Shaun Ruffell (License 5417)
........

Merged revisions 421675 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@421676 65c4cc65-6c06-0410-ace0-fbb531ad65f3