If the compiler supports SSE2, we'll use our SSE2-optimised code
unconditionally. Runtime detection is left for SSSE3 code.
The SSE2 codebase is big and thus a timebomb if an inline function
gets leaked out and run without runtime check. In reality, it's
extremely unlikely people running CPUs without SSE2 support are
running Qt 5 at this moment (they're either too old or too new,
e.g. Intel Quark).
The SSSE3 codebase is a lot more manageable.
Task-number: QTBUG-30440
Change-Id: I3e586e4434e820365d5316b650ee3061d0acf767
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
d006e69da6