Android compile fix

Android is not a proper Linux, and in particular it does not have
pthread_yield().

Change-Id: Ibf94cfacdc24d0c3baaef002c64f9f50c72c01d2
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

tests/auto/corelib/kernel/qmetatype/tst_qmetatype.cpp

@@ -170,7 +170,7 @@ protected:
             const QByteArray name = QString("Bar%1_%2").arg(i).arg((size_t)QThread::currentThreadId()).toLatin1();
             const char *nm = name.constData();
             int tp = qRegisterMetaType<Bar>(nm);
-#ifdef Q_OS_LINUX
+#if defined(Q_OS_LINUX) && !defined(Q_OS_ANDROID)
             pthread_yield();
 #endif
             QMetaType info(tp);