Revert "siso.py: check ninja marker"

This reverts commit 41bbfb8b90.

Reason for revert: 
ukai@ukai ...src/chromium/src % siso ninja -C out/siso
depot_tools/siso.py: Using Siso binary from SISO_PATH: /usr/local/google/home/ukai/go/bin/siso.
Traceback (most recent call last):
  File "/usr/local/google/home/ukai/depot_tools/siso.py", line 115, in <module>
    sys.exit(main(sys.argv))
             ^^^^^^^^^^^^^^
  File "/usr/local/google/home/ukai/depot_tools/siso.py", line 104, in main
    checkOutdir(args[1:])
  File "/usr/local/google/home/ukai/depot_tools/siso.py", line 21, in checkOutdir   
    for i, arg in enumerate(ninja_args):
                            ^^^^^^^^^^
NameError: name 'ninja_args' is not defined. Did you mean: 'ninja_marker'?


Original change's description:
> siso.py: check ninja marker
>
> If out dir was built by Ninja, don't build by Siso.
>
> (still allow `siso query` etc)
>
> Bug: b/338414465
> Change-Id: I48f8fbb5e83714fd3d27ff3a2bfffe929e4ef121
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5518396
> Reviewed-by: Junji Watanabe <jwata@google.com>
> Commit-Queue: Junji Watanabe <jwata@google.com>
> Auto-Submit: Fumitoshi Ukai <ukai@google.com>
> Commit-Queue: Fumitoshi Ukai <ukai@google.com>

Bug: b/338414465
Change-Id: Ie69ca1b6c1d3dc47475d9356beab29a917356479
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5514902
Reviewed-by: Philipp Wollermann <philwo@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Fumitoshi Ukai <ukai@google.com>

siso.py

@@ -15,29 +15,6 @@ import sys
 import gclient_paths
 
 
-def checkOutdir(args):
-    subcmd = ''
-    out_dir = "."
-    for i, arg in enumerate(ninja_args):
-        if not arg.startswith("-") and not subcmd:
-            subcmd = arg
-            continue
-        if arg == "-C":
-            out_dir = ninja_args[i + 1]
-        elif arg.startswith("-C"):
-            out_dir = arg[2:]
-    if subcmd != "ninja":
-        return
-    ninja_marker = os.path.join(out_dir, ".ninja_deps")
-    if os.path.exists(ninja_marker):
-        print("depot_tools/siso.py: %s contains Ninja state file.\n"
-              "Use `autoninja` to use reclient,\n"
-              "or run `gn clean %s` to switch from ninja to siso\n" %
-              (out_dir, out_dir),
-              file=sys.stderr)
-        sys.exit(1)
-
-
 def main(args):
     # Propagate signals to siso process so that it can run cleanup steps.
     # Siso will be terminated immediately after the second Ctrl-C.
@@ -101,7 +78,6 @@ def main(args):
             base_path, 'third_party', 'siso',
             'siso' + gclient_paths.GetExeSuffix())
         if os.path.isfile(siso_path):
-            checkOutdir(args[1:])
             return subprocess.call([siso_path] + args[1:], env=env)
 
     print(