LArCellRec directly references L1CaloCondSvc from TrigT1CaloCondSvc,
which is a class with out-of-line virtual functions.  Thus, it should
link against the library where these functions are defined in order
to see the typeinfo (which it needs) and vtable (which it doesn't
really need).  However, TrigT1CaloCondSvc is built only as a component
library.

Fix this by changing TrigT1CaloCondSvc to a dual use library, and having
LArCellRec link against it.

A better solution would be to rework L1CaloCondSvc in terms of an abstract
interface, so that linking against TrigT1CaloCondSvc would not be
necessary.  However, L1CaloCondSvc has non-trivial templated functions
accessing the class internals, so this is not trivial.
Leaving that for someone else to enjoy doing...