Perfetto UI - 4eae8905e835a9

tp: open files with utf-8 encoding in gen_amalgamted_sql.py (#3343)

Fixes #3342

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In Korean locales it is not unusual that the platform default encoding
on Windows is the EUC-KR codepage, so on these and other systems that
don't default to UTF-8, it would help to have any build script that
loads UTF-8 files make that explicit in their code.

Signed-off-by: Christian W. Damus <cdamus.ext@eclipsesource.com>