vendor: update golang_org/x/net/route from upstream

Updates the route package to git rev 68fc911 for:
- 68fc911 re-adjust routing message alignment for FreeBSD 386 emulation
- 4dfa261 fix typos in comments
- ae89d30 avoid unnecessary type conversions

Change-Id: I915e614e464acf85a8fc80f36f05a85a9246bb01
Reviewed-on: https://go-review.googlesource.com/c/139817
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/vendor/golang_org/x/net/route/interface.go

@@ -37,7 +37,7 @@ func (m *InterfaceAddrMessage) Sys() []Sys { return nil }
 // address message.
 type InterfaceMulticastAddrMessage struct {
 	Version int    // message version
-	Type    int    // messsage type
+	Type    int    // message type
 	Flags   int    // interface flags
 	Index   int    // interface index
 	Addrs   []Addr // addresses

src/vendor/golang_org/x/net/route/sys_freebsd.go

@@ -57,7 +57,7 @@ func (m *InterfaceMessage) Sys() []Sys {
 func probeRoutingStack() (int, map[int]*wireFormat) {
 	var p uintptr
 	wordSize := int(unsafe.Sizeof(p))
-	align := int(unsafe.Sizeof(p))
+	align := wordSize
 	// In the case of kern.supported_archs="amd64 i386", we need
 	// to know the underlying kernel's architecture because the
 	// alignment for routing facilities are set at the build time
@@ -129,6 +129,9 @@ func probeRoutingStack() (int, map[int]*wireFormat) {
 		} else {
 			ifm.bodyOff = sizeofIfMsghdrFreeBSD11
 		}
+		if rel >= 1102000 { // see https://github.com/freebsd/freebsd/commit/027c7f4d66ff8d8c4a46c3665a5ee7d6d8462034#diff-ad4e5b7f1449ea3fc87bc97280de145b
+			align = wordSize
+		}
 	}
 	rtm.parse = rtm.parseRouteMessage
 	ifm.parse = ifm.parseInterfaceMessage

src/vendor/golang_org/x/net/route/syscall.go

@@ -20,7 +20,7 @@ func sysctl(mib []int32, old *byte, oldlen *uintptr, new *byte, newlen uintptr)
 	} else {
 		p = unsafe.Pointer(&zero)
 	}
-	_, _, errno := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(p), uintptr(len(mib)), uintptr(unsafe.Pointer(old)), uintptr(unsafe.Pointer(oldlen)), uintptr(unsafe.Pointer(new)), uintptr(newlen))
+	_, _, errno := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(p), uintptr(len(mib)), uintptr(unsafe.Pointer(old)), uintptr(unsafe.Pointer(oldlen)), uintptr(unsafe.Pointer(new)), newlen)
 	if errno != 0 {
 		return error(errno)
 	}