freefem++ Build-Depends: libhypre-dev, and checks for hypre during
configure.

But in the rest of the build HYPRE is not actually used.  There are
files that include hypre headers in src/solver and in examples++-mpi, but the
examples build doesn't invoke the hypre files.  src/solver isn't being used at all.

I'm not sure if it means the configure or Makefile.am settings should be
patched, or if Build-Depends: libhypre-dev should just be removed.