Revert "Switch to new vendor directory layout"

This reverts commit d5742209d3.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

vendor/github.com/opencontainers/runc/libcontainer/nsenter/nsenter_gccgo.go

@@ -1,25 +0,0 @@
-// +build linux,gccgo
-
-package nsenter
-
-/*
-#cgo CFLAGS: -Wall
-extern void nsexec();
-void __attribute__((constructor)) init(void) {
-	nsexec();
-}
-*/
-import "C"
-
-// AlwaysFalse is here to stay false
-// (and be exported so the compiler doesn't optimize out its reference)
-var AlwaysFalse bool
-
-func init() {
-	if AlwaysFalse {
-		// by referencing this C init() in a noop test, it will ensure the compiler
-		// links in the C function.
-		// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65134
-		C.init()
-	}
-}