Changes the requirement of a Runtime v2 shim in order to avoid race conditions
between shim and shim client sending async events. Places a requirement of what
events and what order a shim must comply to.
Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>
A fifo on unix or named pipe on Windows will be provided to the shim.
It can be located inside the `cwd` of the shim named "log".
The shims can use the existing `github.com/containerd/containerd/log` package to log debug messages.
Messages will automatically be output in the containerd's daemon logs with the correct fiels and runtime set.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
