win: Delete the pdb before linking an exe for official

build/toolchain/win/tool_wrapper.py

Index: build/toolchain/win/tool_wrapper.py
diff --git a/build/toolchain/win/tool_wrapper.py b/build/toolchain/win/tool_wrapper.py
index 54e177cee2e5f302ed389478f54220a68fde110e..281298c65c2aabe4100ad320917c2cc7aaeecbc3 100644
--- a/build/toolchain/win/tool_wrapper.py
+++ b/build/toolchain/win/tool_wrapper.py
@@ -85,6 +85,11 @@ class WinTool(object):
     """Simple stamp command."""
     open(path, 'w').close()
 
+  def ExecDeleteFile(self, path):
+    """Simple file delete command."""
+    if os.path.exists(path):
+      os.unlink(path)
+
   def ExecRecursiveMirror(self, source, dest):
     """Emulation of rm -rf out && cp -af in out."""
     if os.path.exists(dest):