xsdk-0.4.0: add/update package versions: (#10038)

* xsdk-0.4.0: add/update package versions:
  hypre@2.15.1
  mfem@3.4.0
  superlu-dist@6.1.0
  trilinos@12.14.0-rc1
  petsc@3.10.3
  dealii@9.0.1
  pflotran@xsdk-0.4.0
  alquimia@xsdk-0.4.0
  sundials@3.2.1
  plasma@18.11.1
  magma@2.4.0
  amrex@18.10.1
  slepc@3.10.1
  omega-h@9.19.1
  strumpack@3.1.1
  pumi@2.2.0
  tasmanian@6.0
  phist@1.7.5
  dtk-3.0 [via trilinos features '+dtk+intrepid2+shards']

add option to disable omega-h build [wrt gcc-8 conflict]
  spack install xsdk~omega-h
add option to disable dealii build [wrt cori build error]
  spack install xsdk~dealii

* trilinos: default version should be the prior release