UBUNTU: SAUCE: LSM: Use lsmblob in security_secctx_to_secid
Change security_secctx_to_secid() to fill in a lsmblob instead
of a u32 secid. Multiple LSMs may be able to interpret the
string, and this allows for setting whichever secid is
appropriate. Change security_secmark_relabel_packet() to use a
lsmblob instead of a u32 secid. In some other cases there is
scaffolding where interfaces have yet to be converted.