Pre-allocate transmission data buffer for RLS NOTIFY requests.

PJSIP, unless a constant is modified at compilation time, limits
SIP requests to 4000 bytes. Full-state RLS notifications can easily
exceed this limit with moderately small lists.

This changeset allows for Asterisk to work around this size limit by
performing its own allocation of the transmission data buffer. This
way, Asterisk can allocate a buffer that exceeds the built-in maximum.

We still impose our own limit of 64000 bytes, mainly because making
allocations larger than that is a bit absurd.

ASTERISK-24181 #close
Reported by Mark Michelson

Review: https://reviewboard.asterisk.org/r/3977
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Merged revisions 422851 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@422852 f38db490-d61c-443f-a65b-d21fe96a405b
Add sample configuration for resource lists.

On review /r/3977, it was recommended to note in the
sample configuration about the size limitation for
resource lists. However, since there was no section in
the sample configuration at all for resource list
subscriptions, I decided to make a separate commit
where I have added the necessary sample configuration
as well as the size limitation warning.
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Merged revisions 422853 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@422854 f38db490-d61c-443f-a65b-d21fe96a405b
Add note about configuring list_items on a single line.
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Merged revisions 422855 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@422856 f38db490-d61c-443f-a65b-d21fe96a405b