In tests/unit/makefile, always use the full path to the source files - this is needed as a workaround for an issue in Coveralls when run in Travis CI.
In tests/unit/makefile, always use the full path to the source
files - this is needed as a workaround for an issue in Coveralls
when run in Travis CI.

mfem/mfem,mfem/mfem,mfem/mfem,mfem/mfem,mfem/mfem