VOL-1497 : Add more control to kv/memory access

- Added kv locking mechanism (etcd only)
- (watch) control path access whenever possible
- (watch) use a transaction for updates and merge with memory
- cleaned up vendoring
- misc changes to fix exceptions found along the way

Amendments:

- Copyright header got removed in auto-generated file
- Changed default locking to false for KV list operation
- Updated backend api to allow the passing of locking parameter

Change-Id: Ie1a55d3ca8b9d92ae71a85ce42bb22fcf1419e2c
diff --git a/vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go b/vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go
index b50178d..c142e33 100644
--- a/vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go
+++ b/vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go
@@ -943,6 +943,21 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func ClockGettime(clockid int32, time *Timespec) (err error) {
+	_, _, e1 := syscall_syscall(funcPC(libc_clock_gettime_trampoline), uintptr(clockid), uintptr(unsafe.Pointer(time)), 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func libc_clock_gettime_trampoline()
+
+//go:linkname libc_clock_gettime libc_clock_gettime
+//go:cgo_import_dynamic libc_clock_gettime clock_gettime "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Close(fd int) (err error) {
 	_, _, e1 := syscall_syscall(funcPC(libc_close_trampoline), uintptr(fd), 0, 0)
 	if e1 != 0 {