siso: call checkOutdir to prevent from running siso in ninja's out

checkOutdir should be called before run `siso ninja`
to not run `siso ninja` where `ninja` is used.

Change-Id: I55453b21d35396b59924be5398b47f67b592eca1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5802658
Reviewed-by: Philipp Wollermann <philwo@google.com>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Auto-Submit: Fumitoshi Ukai <ukai@google.com>
Commit-Queue: Fumitoshi Ukai <ukai@google.com>

siso.py

@@ -112,6 +112,7 @@ def main(args):
         ]
         for siso_path in siso_paths:
             if siso_path and os.path.isfile(siso_path):
+                checkOutdir(args[1:])
                 return subprocess.call([siso_path] + args[1:], env=env)
     if siso_override_path:
         return subprocess.call([siso_override_path] + args[1:])