tools: ynl: add script dir to sys.path

Python options like PYTHONSAFEPATH or -P [1] do not add script
directory to PYTHONPATH. ynl depends on this path to build and run.

[1] This option is default for Fedora rpmbuild since introduction of
    https://fedoraproject.org/wiki/Changes/PythonSafePath

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/b26537cdb6e1b24435b50b2ef81d71f31c630bc1.1731399562.git.jstancek@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/cli.py

@@ -3,10 +3,13 @@
 
 import argparse
 import json
+import pathlib
 import pprint
+import sys
 import time
 import signal
 
+sys.path.append(pathlib.Path(__file__).resolve().parent.as_posix())
 from lib import YnlFamily, Netlink, NlError
 
 

tools/net/ynl/ethtool.py

@@ -3,11 +3,13 @@
 
 import argparse
 import json
+import pathlib
 import pprint
 import sys
 import re
 import os
 
+sys.path.append(pathlib.Path(__file__).resolve().parent.as_posix())
 from lib import YnlFamily
 
 def args_to_req(ynl, op_name, args, req):

tools/net/ynl/ynl-gen-c.py

@@ -4,12 +4,15 @@
 import argparse
 import collections
 import filecmp
+import pathlib
 import os
 import re
 import shutil
+import sys
 import tempfile
 import yaml
 
+sys.path.append(pathlib.Path(__file__).resolve().parent.as_posix())
 from lib import SpecFamily, SpecAttrSet, SpecAttr, SpecOperation, SpecEnumSet, SpecEnumEntry