Fix incorrect usages of ast_realloc().
There are several locations in the code base where this is done:
buf = ast_realloc(buf, new_size);
This is going to leak the original buf contents if the realloc fails.
Review: https://reviewboard.asterisk.org/r/2832/
........
Merged revisions 398757 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........
Merged revisions 398758 from http://svn.asterisk.org/svn/asterisk/branches/11
........
Merged revisions 398759 from http://svn.asterisk.org/svn/asterisk/branches/12
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@398760
65c4cc65-6c06-0410-ace0-
fbb531ad65f3