Fix bug in gyp_webrtc.py when DEPOT_TOOLS_WIN_TOOLCHAIN=0

In https://codereview.webrtc.org/1895713002 a bug was introduced
in order to satisfy the PyLint check.

BUG=webrtc:5911
NOTRY=True
R=phoglund@webrtc.org

Review URL: https://codereview.webrtc.org/1992813006 .

Cr-Commit-Position: refs/heads/master@{#12810}
diff --git a/webrtc/build/gyp_webrtc.py b/webrtc/build/gyp_webrtc.py
index 2d44971..0572948 100755
--- a/webrtc/build/gyp_webrtc.py
+++ b/webrtc/build/gyp_webrtc.py
@@ -86,7 +86,7 @@
       os.environ['GYP_GENERATOR_FLAGS'] = (
           gyp_generator_flags + ' msvs_error_on_missing_sources=1')
 
-  vs2013_runtime_dll_dirs = None, None
+  vs2013_runtime_dll_dirs = None
   if int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1')):
     vs2013_runtime_dll_dirs = vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
 
@@ -116,6 +116,7 @@
   gyp_rc = gyp.main(args)
 
   if vs2013_runtime_dll_dirs:
+    # pylint: disable=unpacking-non-sequence
     x64_runtime, x86_runtime = vs2013_runtime_dll_dirs
     vs_toolchain.CopyVsRuntimeDlls(
         os.path.join(checkout_root, gyp_chromium.GetOutputDirectory()),