Avoid asan errors

The SSE code can read slightly outside the bounds of the string.
This is ok, as it's limited to 16 byte boundaries and thus can't
cause a segfault. But it does cause a crash with asan.

Change-Id: Id6e4a550579dc6228f365357773b392ecfd41471
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/corelib/text/qstring.cpp

@@ -163,7 +163,7 @@ qsizetype QtPrivate::qustrlen(const ushort *str) noexcept
 {
     qsizetype result = 0;
 
-#ifdef __SSE2__
+#if defined(__SSE2__) && !(defined(__SANITIZE_ADDRESS__) || QT_HAS_FEATURE(address_sanitizer))
     // find the 16-byte alignment immediately prior or equal to str
     quintptr misalignment = quintptr(str) & 0xf;
     Q_ASSERT((misalignment & 1) == 0);