FinKexiv2: Use FindPkgConfig instead of UsePkgConfig
Review Request #123437 - Created April 20, 2015 and submitted - Latest diff uploaded
The latter is deprecated and doesn't respect the PKG_CONFIG environment variable which makes it easy to deal with differently named pkg-config executables, e.g. arch-prefixed ones.
I built okular and checked that it finds and links against libkexiv2.