wpa_supplicant: fix static linking

wpa_supplicant doesn't use pkg-config and upstream likely wouldn't take
a patch to do so (hostapd/wpa_supplicant are used in android builds, and
it doesn't use any auto* stuff either) so pass it in LIBS* since we
always build openssl with libz support.

Made ugly by the fact that wpa_supplicant uses LIBS for the
wpa_supplicant binary, LIBS_c for the wpa_cli binary and LIBS_p for the
wpa_passphrase binary.

Also do f62a1d88 here too since it
applies when libnl is used.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>