instsoft.GRMLBASE: ensure that file-rc can be installed

If we request installation of file-rc but don't add hint
to remove systemd-sysv package then aptitude fails with:

| The following NEW packages will be installed:
|   file-rc initscripts{a} insserv{a} sysvinit-core{ab}
| The following packages are RECOMMENDED but will NOT be installed:
|   psmisc
| 0 packages upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
| Need to get 316 kB of archives. After unpacking 686 kB will be used.
| The following packages have unmet dependencies:
|  systemd-sysv : Conflicts: file-rc but 0.8.18 is to be installed
|                 Conflicts: sysvinit-core but 2.88dsf-59.8 is to be installed
|  sysvinit-core : Conflicts: systemd-sysv but 232-3 is installed
| The following actions will resolve these dependencies:
|
|      Install the following packages:
| 1)     startpar [0.59-3.1 (testing)]
| 2)     sysv-rc [2.88dsf-59.8 (testing)]
|
|      Keep the following packages at their current version:
| 3)     file-rc [Not Installed]
| 4)     sysvinit-core [Not Installed]
|
|
|
| No packages will be installed, upgraded, or removed.
| 0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.