gss_krb5: use lcm from kernel lib
gss_krb5: use lcm from kernel lib

Replace hardcoded lowest common multiple algorithm by the lcm()
function in kernel lib.

Signed-off-by: Luis Henriques <4e624af203c18e164acadf5da06f2c9f36828cb4@canonical.com>
Signed-off-by: J. Bruce Fields <51738506c1b2ccb0761f23bdc612c93babf738ea@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs