test1112: Increase the timeout from 7s to 16s

As someone reported on the mailing list a while back, the hard-coded
arbitrary timeout of 7s in test 1112 is not sufficient in some build
environments. At Arista Networks we build and test curl as part of our
automated build system, and we've run into this timeout 170 times so
far. Our build servers are typically quite busy building and testing a
lot of code in parallel, so despite being beefy machines with 32 cores
and 128GB of RAM we still hit this 7s timeout regularly.

URL: http://curl.haxx.se/mail/lib-2010-02/0200.html