Re: [libvirt] [PATCHv2 10/15] security: add new virSecurityManagerSetChildProcessLabel API

The existing virSecurityManagerSetProcessLabel() API is designed so that it must be called after forking the child process, but before exec'ing the child. Due to the way the virCommand API works, that means it needs to be put in a "hook" function that virCommand is told to call out to at that time.

With this new API in place, we will be able to remove virSecurityManagerSetProcessLabel() from any virCommand pre-exec hooks. (Unfortunately, the LXC driver uses clone() rather than virCommand, so it can't take advantage of this new security driver API, meaning that we need to keep around the older virSecurityManagerSetProcessLabel(), at least for now.) --- Change from V1: rebased, Copyright dates simplified.