The Edison deployment is using a Libs: line that looks like this in pkgconfig:

Libs: ${darshan_linkopts} ${darshan_libdir} -lfmpich -lmpichcxx -Wl,--start-group -ldarshan-mpi-io -ldarshan-posix -ldarshan-stubs -Wl,--end-group

We should add this start-group and end-group setup to the repository as well. It helps with some link-time corner cases.