Fix netcdf variant (+mpi) on Compy

Author: xylar

mache/spack/compy_intel_impi.yaml

@@ -129,7 +129,7 @@ spack:
       buildable: false
     netcdf-c:
       externals:
-      - spec: netcdf-c~[email protected]
+      - spec: netcdf-c+[email protected]
         prefix: /share/apps/netcdf/4.6.3/intel/20.0.0
         modules:
         - netcdf/4.6.3