libpjsip: fix ssl support

libpjsip: fix ssl support

Currently, ssl support is implicitely disabled in the initial configure
options. This overrides the check for openssl below.

libpjsip is also currently only compatible with libopenssl. Change
the check to LIBOPENSSL instead of openssl, and depend on libopenssl.

[Peter: drop libopenssl change]
Signed-off-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
(cherry picked from commit 9e479e65dcf1582b20433ca1b120efb66e806a04)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>