znc: fix QA issue and remove from blacklist

Modify the .pc file to fix the following QA problem.

  "BROKEN: QA Issue: znc.pc failed sanity test"

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>