syscall: implement Reboot for linux.

The published interface is the simple version of the syscall,
allowing all reboot functions except for the esoteric
LINUX_REBOOT_CMD_RESTART2.

R=golang-dev, bradfitzgo, bradfitzwork
CC=golang-dev
https://golang.org/cl/4256060
diff --git a/src/pkg/syscall/zsyscall_linux_amd64.go b/src/pkg/syscall/zsyscall_linux_amd64.go
index d449a3b..b688ecf 100644
--- a/src/pkg/syscall/zsyscall_linux_amd64.go
+++ b/src/pkg/syscall/zsyscall_linux_amd64.go
@@ -81,6 +81,14 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func reboot(magic1 uint, magic2 uint, cmd int, arg string) (errno int) {
+	_, _, e1 := Syscall6(SYS_REBOOT, uintptr(magic1), uintptr(magic2), uintptr(cmd), uintptr(unsafe.Pointer(StringBytePtr(arg))), 0, 0)
+	errno = int(e1)
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Access(path string, mode uint32) (errno int) {
 	_, _, e1 := Syscall(SYS_ACCESS, uintptr(unsafe.Pointer(StringBytePtr(path))), uintptr(mode), 0)
 	errno = int(e1)