Allows yuzu to be built with Clang 15

Silences a truncation warning by making the truncation explicit and
documenting the reason for it.

Cleans up common so that we can enable warnings as errors.

Recent changes to the build system that made more warnings be flagged as
errors caused building via clang to break.

Fixes #4795

As reported by tsan, g_bUseLock had a data race. Fix this using an
atomic boolean.

Two of the members of the MicroProfileThreadLog contains two std::atomic
instances. Given these aren't trivially-copyable types, we shouldn't be
memsetting the structure, given implementation details can contain other
members within it.

To avoid potential undefined behavior on platforms, we can use aggregate
initialization to zero out the members while still having well-defined
behavior.

While we're at it we can also silence some sign conversion warnings.