build: fix dependency on execinfo for BSD meson builds

build: fix dependency on execinfo for BSD meson builds

The binaries and apps in DPDK all need to be linked against the
execinfo library on FreeBSD so add this as a dependency in cases
where it is found. It's available by default on BSD, but not
at all on Linux

Fixes: 16ade738fd0d ("app/testpmd: build with meson")
Fixes: 89f0711f9ddf ("examples: build some samples with meson")
Fixes: b5dc795a8a55 ("test: build app with meson as dpdk-test")
Fixes: 2ff67267b049 ("app/eventdev: build with meson")
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>