Makefile: Make pkg-config mandatory to find libpci

Use `make HAS_LIBPCI=yes/no` to override the pkg-config detection and
`CONFIG_LIBPCI_CFLAGS` and `CONFIG_LIBPCI_LDFLAGS` to set cflags and
ldflags manually. The optional dependency of libpci libz, is
automatically handled by pkg-config.

Change-Id: I21b4a261b34b7e688635fc6e20b7beebfa64c7ed
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
---
M Makefile
A Makefile.d/pci_old_get_dev_test.c
M Makefile.include
3 files changed, 65 insertions(+), 131 deletions(-)