Add an SSE4.2 even simpler version of toLatin1

Add an SSE4.2 even simpler version of toLatin1

Use the new PCMPESTRM instruction (Parallel CoMPare Explicit-length
STRings with result in a Mask) which is added in SSE4.2 for
facilitating string operations. The "compare ranges" mode allows us to
search for characters outside the Latin 1 range and then use the
SSE4.1 PBLENDVB instruction to replace those with question marks.

Unlike previous SSE compare instructions, the PCMPxSTRx family allows
us to operate on unsigned 16-bit values. This saves us another
parallel add.

Reviewed-By: Samuel Rødal
(cherry picked from commit 45d2d36c9dbcbce403c78838ea52acd1ab111b68)

Change-Id: I0f9d864f9d19c0f0da43ccb6918dc28295074496
Reviewed-on: http://codereview.qt-project.org/4468
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>