Migration report: validate that bc is installed
Migration report: validate that bc is installed

Without this the tool reports:

gkotton@ubuntu:~/neutron-lib$ ./tools/migration_report.sh ../vmware-nsx/
You have 2517 total imports
You imported Neutron 477 times
You imported Neutron-Lib 108 times
./tools/migration_report.sh: line 30: bc: command not found
./tools/migration_report.sh: line 31: bc: command not found
./tools/migration_report.sh: line 33: [: : integer expression expected

Closes-bug: #1604438

Change-Id: Ib8236ae214d423c993d9e22035f70af1821af944

openstack/neutron-lib,openstack/neutron-lib,openstack/neutron-lib,openstack/neutron-lib