Linking error with muParser on Fedora

Summary

When building GROMACS with externally linked muParser, builds fail due to linker errors. Example reported by the Fedora project, build here: https://koji.fedoraproject.org/koji/taskinfo?taskID=92400080

GROMACS version

Failed build was with 2022.3, but likely affects all versions that allow linking to external muParser.

Steps to reproduce

Try building GROMACS against muParser with release version 2.3.3 on Fedora. Set following in addition to regular commands on CMake command line: -DGMX_USE_MUPARSER=EXTERNAL

What is the current bug behavior?

GROMACS build fails in the linking stage due to undefined symbols. I confirmed that there are no changes of the muParser API, so this is only due to failure to link properly.

What did you expect the correct behavior to be?

Either we shouldn't accept the external library, or we should be able to build with it.

Possible fixes

Fix linking flags in CMake.