Follow up to r20700 - it turns out that *one* of those seemingly-bogus mentions of 'neon' was actually a workaround for a libtool bug. Reintroduce it, *also* adding it to the two other cases which were similar, and this time add a large comment explaining the issue so that in future people are not left wondering as to its presence, and aren't tempted to clean it up.
Follow up to r20700 - it turns out that *one* of those seemingly-bogus mentions
of 'neon' was actually a workaround for a libtool bug. Reintroduce it, *also*
adding it to the two other cases which were similar, and this time add a large
comment explaining the issue so that in future people are not left wondering
as to its presence, and aren't tempted to clean it up.

* build.conf: Add neon dependency to svn, svnsync, and ra-local-test.
    Add comment explaining why.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion