corrected grompp rvdw charge-group radii check

The grompp note for charge-group radii larger than the buffer size
for VdW interactions only checked for rlist, not rlistlong.
Fixes #1164

Change-Id: I85a615e6c004503440bcae52c220540a843107d0
Merge "corrected grompp rvdw charge-group radii check" into release-4-6