build: fix check for libbsd in meson

build: fix check for libbsd in meson

When we check for libbsd we were just checking for the library itself.
However, on some distros, e.g. CentOS, libbsd will be found even though
it's not usable by DPDK as it's missing the string header. Therefore we
should check for both the library and the header file.

Fixes: 5364de644a4b ("eal: support strlcpy function")

Signed-off-by: Bruce Richarson <bruce.richardson@intel.com>
Reported-by: Vladimir Medvedkin <medvedkinv@gmail.com>
Acked-by: Vladimir Medvedkin <medvedkinv@gmail.com>
Acked-by: Luca Boccassi <bluca@debian.org>