config-checks.mk: check if jack.pc >= 0.124.0 is present
config-checks.mk: check if jack.pc >= 0.124.0 is present

The 0.124 version of libjack is supplied by Xenial.

Signed-off-by: Tim Janik <6ec6ff229c4e1c5bbd5933ee92e6c5832ff023bb@gnu.org>

tim-janik/beast,swesterfeld/beast,tim-janik/beast,tim-janik/beast,swesterfeld/beast,swesterfeld/beast,swesterfeld/beast,tim-janik/beast,swesterfeld/beast,tim-janik/beast,tim-janik/beast,swesterfeld/beast,tim-janik/beast,swesterfeld/beast