Added -lpthread to pkgconfig file.
Added -lpthread to pkgconfig file.

retrieva/pficommon,pfi/pficommon,pfi/pficommon,retrieva/pficommon,retrieva/pficommon,takei-yuya/pficommon,pfi/pficommon,takei-yuya/pficommon,takei-yuya/pficommon,retrieva/pficommon,pfi/pficommon,takei-yuya/pficommon,retrieva/pficommon