netcat-openbsd: fix qa warning

fix for QA Warning: No GNU_HASH in elf binary, it won't obey the default
LDFLAGS which results in QA Warning while building with external toolchain,
so adding the default LDFLAGS.

WARNING: netcat-openbsd-1.105-r0 do_package_qa:QA Issue: No GNU_HASH in the
elf binary:..nc.netcat-openbsd' [ldflags]

Signed-off-by: Shrikant Bobade <shrikant_bobade@mentor.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>
(cherry picked from commit d765990dd2fc9324963e9ecb0f93b7e613e874ad)
Signed-off-by: Armin Kuster <akuster808@gmail.com>