Add missing library directory flag in pkgconfig file
Add missing library directory flag in pkgconfig file

Signed-off-by: Andrei Lebedev <b7c51ea8b212e9b6861d50c54adce22dd5b75067@gmail.com>

google/libprotobuf-mutator,vitalybuka/libprotobuf-mutator,vitalybuka/libprotobuf-mutator,google/libprotobuf-mutator