LP#1464748: don't toss terminal account information prematurely

LP#1464748: don't toss terminal account information prematurely

This patch ensures that when the PreFork Net::Server personality
is in use, terminal login information is not prematurely cleared
between *_transport() and sip_protocol_loop().  This, in conjunction
with the patch for bug 1463459, fixes a problem where a SIP
client that connects, issues a 93 request, then a 99 request, could
get an incorrect 98 response.

To test fixes for 1463459 and 1464748:

[1] Set up a SIP configuration with at least two institutions
    with different capabilities and at least one account
    for each institution.  Assume that account A1 is for
    institution I1 and A2 for I2.

[2] Prior to applying the patches for 1463459 and 1464748,
    start the SIP server and try the following sequence:

    a. 93 to log in as A2
    b. 99 to get SC status
    c. Note that the 98 response has values for I1, not I2

[3] Apply the patches and restart SIP, then repeat the steps
    in [2].  This time, the 98 response should have the
    values for I2.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>