Fix xtree patch check, and in turn C4702 disabling

build/win_is_xtree_patched.py

Index: build/win_is_xtree_patched.py
diff --git a/build/win_is_xtree_patched.py b/build/win_is_xtree_patched.py
index 571732272f54658d732036da040ce1dae9bc4cd0..3f1994ff9d1749b69e9c26130a60c615bfc80701 100755
--- a/build/win_is_xtree_patched.py
+++ b/build/win_is_xtree_patched.py
@@ -13,13 +13,13 @@ def IsPatched():
   # script (because we know it's patched). Another case could be added here to
   # query the active VS installation and actually check the contents of xtree.
   # http://crbug.com/346399.
-  return os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', 1) == 0
+  return int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', 1)) == 1
 
 
 def DoMain(_):
   """Hook to be called from gyp without starting a separate python
   interpreter."""
-  return IsPatched()
+  return "1" if IsPatched() else "0"
 
 
 if __name__ == '__main__':