Allow bootstrap script to work on Solaris.

As usual, the way they do things is different, so we need to account for that.
automake is versioned ala BSD/Linux, but autoconf is not.  We don't actually
need to specify a version there, since AC_PREREQ will cover it for us.  Things
will fail pretty loudly if AC_PREREQ isn't met.

(closes issue #16341)
Reported by: bklang
Patches: 
      opensolaris_bootstrap.sh uploaded by bklang (license 919)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@262299 65c4cc65-6c06-0410-ace0-fbb531ad65f3