TraceProcessor: optimize std::sort<TimestampedTracePiece>

TraceSorter::Sort() is a very hot path in trace processor.
That does a std::sort on a CircularQueue<TTP>.
std::sort uses std::swap, which falls back on 2 std::moves
when not implemented.
TTP happens to be precisely 512-bits wide. This allows to
implement a very efficient swap which leverages XMM registers
on x86_64.
This saves 7-10% of trace ingestion time on a large trace.

Bug: 205302474
Change-Id: Ie57fc26e79599b2e27945dc5cef176c1d03d95cc