container: unexport PR_SET_NO_NEW_PRIVS wrapper

This is subtle to use correctly. It also does not make sense as part of the container API.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/container.go

@@ -307,7 +307,7 @@ func (p *Container) Start() error {
 		done <- func() error {
 			// PR_SET_NO_NEW_PRIVS: thread-directed but acts on all processes
 			// created from the calling thread
-			if err := SetNoNewPrivs(); err != nil {
+			if err := setNoNewPrivs(); err != nil {
 				return &StartError{
 					Fatal: true,
 					Step:  "prctl(PR_SET_NO_NEW_PRIVS)",