Ensure that every package has a description (#10896)

lib/spack/spack/test/package_sanity.py

var/spack/repos/builtin/packages/apex/package.py

var/spack/repos/builtin/packages/bamdst/package.py

var/spack/repos/builtin/packages/ecflow/package.py

var/spack/repos/builtin/packages/elk/package.py

var/spack/repos/builtin/packages/libpcap/package.py

var/spack/repos/builtin/packages/libspatialindex/package.py

var/spack/repos/builtin/packages/libxsmm/package.py

var/spack/repos/builtin/packages/libxstream/package.py

var/spack/repos/builtin/packages/mysql/package.py

.../repos/builtin/packages/perl-compress-raw-zlib/package.py

var/spack/repos/builtin/packages/py-astroid/package.py

var/spack/repos/builtin/packages/sofa-c/package.py