This formats all copyright comments according to SPDX formatting guidelines.
Additionally, this resolves the remaining GPLv2 only licensed files by relicensing them to GPLv2.0-or-later.
We can simplify this function down into a single line with the use of
fmt. A benefit with the fmt approach is that the fmt variant of
localtime is thread-safe as well, making GetOsTimeZoneOffset()
thread-safe as well.
