build: skip detecting libpcap via pcap-config

build: skip detecting libpcap via pcap-config

When compiling for a slightly different architecture, e.g. 32-bit on 64-bit
systems using CFLAGS rather than a cross-file, the pcap-config utility can
often return parameters that are unusable for the build in question, i.e.
providing the native 64-bit library paths rather than checking for 32-bit
equivalent.

Since many distros now include a version of libpcap with a
pkg-config file, and for those that don't find-library should work ok as a
fallback, we can explicitly just use pkg-config in the dependency search,
causing meson to skip trying to use pcap-config.

Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Luca Boccassi <bluca@debian.org>
Tested-by: David Marchand <david.marchand@redhat.com>