Gromacs installs internal muparser header files
The configuration of the bundled muparser library installs all its header files under the Gromacs include directory.
While it might be necessary to export the dynamic library such that external tools can link with Gromacs, I would presume the Gromacs build and interfaces should not depend on exactly what library we use internally to parse mathematical expressions.
I found this because I bumped into a similar issue when trying to add the fmt library.