Fixes building against static libssl:
http://autobuild.buildroot.net/results/7edb3756a07bbac27f852332b81677feb6156a48/
The major change between 2.16 and 2.16.1 that fixes static linking
with libssl is that pkg-config is now used to detect
libssl. Therefore, we add a dependency on host-pkgconf.
Signed-off-by: Ismael Luceno <ismael@iodev.co.uk>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>