export fswatcher to a separate library

vendor/golang.org/x/sys/unix/ptrace_darwin.go

@@ -7,6 +7,12 @@
 
 package unix
 
+import "unsafe"
+
 func ptrace(request int, pid int, addr uintptr, data uintptr) error {
 	return ptrace1(request, pid, addr, data)
 }
+
+func ptracePtr(request int, pid int, addr uintptr, data unsafe.Pointer) error {
+	return ptrace1Ptr(request, pid, addr, data)
+}