Don't check if Pentium's CPUID leaf 1 exists

It does. When CPUID was introduced in late 486, it already supported
leaf 1. That means all Pentium-class systems (including Intel's new
Quark systems) have CPUID and they have at least leaf 1.

Change-Id: Ib306f8f647014b399b87ffff13f1d5d2530d9ddd
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qsimd.cpp

@@ -258,8 +258,12 @@ static inline uint detectProcessorFeatures()
 
     uint features = 0;
     int cpuidLevel = maxBasicCpuidSupported();
+#if Q_PROCESSOR_X86 < 5
     if (cpuidLevel < 1)
         return 0;
+#else
+    Q_ASSERT(cpuidLevel >= 1);
+#endif
 
     uint cpuid01ECX = 0, cpuid01EDX = 0;
     cpuidFeatures01(cpuid01ECX, cpuid01EDX);