Change ${LCIO_LIBRARIES} to LCIO::lcio

[jmcarcell]

BEGINRELEASENOTES

• Change ${LCIO_LIBRARIES} to LCIO::lcio in CMakeLists.txt for cases when LCIO_LIBRARIES is empty. Also prevents linking to SIO when it's not necessary but it's included in LCIO_LIBRARIES

ENDRELEASENOTES

This is the same as iLCSoft/LCCD#7

[tmadlener]

I am not entirely sure how $LCIO_LIBRARIES would be empty, and if it is whether we should not fix it upstream in LCIO instead of introducing workarounds in several downstream repositories.

[jmcarcell]

PR updated, now works with iLCSoft/LCIO#177

I am not entirely sure how $LCIO_LIBRARIES would be empty, and if it is whether we should not fix it upstream in LCIO instead of introducing workarounds in several downstream repositories.

If you build together (at the same time) LCIO with another package then LCIO_LIBRARIES won't be set; one could set LCIO_LIBRARIES manually for this case to lcio and it will work. In this case where it's a single library that doesn't change over time we can use the target and have all build workflows working.

[andresailer]

Superseded by #298