Fix build with GCC <= 4.2 (FreeBSD 9.x)

15b42af111 changed the qt_cpu_features
variable to be an array and never fixed this #if branch of the code.

Change-Id: Id69569111e7d4e619e22ffff144cf930f86f478e
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/corelib/tools/qsimd.cpp

@@ -666,7 +666,11 @@ void qDetectCpuFeatures()
     // contains all the features that the code required. Qt 4 ran for years
     // like that, so it shouldn't be a problem.
 
-    qt_cpu_features.store(minFeature | quint32(QSimdInitialized));
+    qt_cpu_features[0].store(minFeature | quint32(QSimdInitialized));
+#ifndef Q_ATOMIC_INT64_IS_SUPPORTED
+    qt_cpu_features[1].store(minFeature >> 32);
+#endif
+
     return;
 # endif
 #endif