export fswatcher to a separate library

vendor/golang.org/x/sys/execabs/execabs_go119.go

@@ -15,3 +15,7 @@ import (
 func isGo119ErrDot(err error) bool {
 	return errors.Is(err, exec.ErrDot)
 }
+
+func isGo119ErrFieldSet(cmd *exec.Cmd) bool {
+	return cmd.Err != nil
+}