Makefile: Make pkg-config mandatory to find libjaylink

Use `make HAS_LIBJAYLINK=yes/no` to override the pkg-config detection
and `CONFIG_LIBJAYLINK_CFLAGS` and `CONFIG_LIBJAYLINK_LDFLAGS` to set
cflags and ldflags manually.

Change-Id: I99df547046bb9820ab502f89f6d4452c1bc0cfd4
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/59048
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72262
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2 files changed