message: Use real compiler for MFEM instead of Spack's wrapped compiler
diff: @@ -263,7 +263,7 @@ class Mfem(Package):
  'MFEM_DEBUG=%s' % yes_no('+debug'),
  # NOTE: env['CXX'] is the spack c++ compiler wrapper. The real
  # compiler is defined by env['SPACK_CXX'].
  - 'CXX=%s' % env['CXX'],
  + 'CXX=%s' % env['SPACK_CXX'],
  'MFEM_USE_LIBUNWIND=%s' % yes_no('+libunwind'),
  'MFEM_USE_GZSTREAM=%s' % yes_no('+gzstream'),
  'MFEM_USE_METIS=%s' % yes_no('+metis'),
  