Fix `create_chrome_version_h` in bootstrap.py

Fix `create_chrome_version_h` in bootstrap.py

The code was supposed to compare the content of the existing file with
the new content and only replace the file if the content was different,
but it had a fatal flow. It opened the existing file with 'w+' or 'wb+'
and they both truncate the file, so the compare was always false and we
always overwrote the file.
The updated code compares the file content ignoring line endings and
writes the file only if its different or if it didn't exist.