Update o2.pc.cmake to include '-lo2'
Update o2.pc.cmake to include '-lo2'

Using @CMAKE_LIBRARY_PATH@ in Libs didn't make sense, since it generates
a "Semicolon-separated list of directories...". Hard code it to -lo2
instead since it works for both shared and static libraries, and we have
no configuration setting to change the name of the library.

pipacs/o2,pipacs/o2