Add generation / installation of pkg-config files. (Bobby Powers)

git-svn-id: https://protobuf-c.googlecode.com/svn/trunk@221 00440858-1255-0410-a3e6-75ea37f81c3a

ChangeLog

 0.14 (NOT YET RELEASED)
       - build fix (missing dependency in test directory)
+      - add generation / installation of pkg-config files. (Bobby Powers)
+
 0.13:
       - Fix for when the number of connections gets too great in RPC.
         (Leszek Swirski) (issue #32)