Ensure that qXXXdetection.h can be included directly

Those files might have dependency on one another, on qconfig.h and on
early qglobal.h definitions, so ensure that the only correct include
order is that of qglobal.h.

Change-Id: I89098bacaf16353ee8b51604ee885508dc8e201a
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

config.tests/arch/arch.cpp

@@ -40,6 +40,7 @@
 ****************************************************************************/
 
 // NOTE: This file is not meant to be compiled, only preprocessed.
+#define QGLOBAL_H
 #include "../../src/corelib/global/qprocessordetection.h"
 #undef alpha
 #undef arm

src/corelib/global/qcompilerdetection.h

@@ -40,6 +40,10 @@
 **
 ****************************************************************************/
 
+#ifndef QGLOBAL_H
+# include <QtCore/qglobal.h>
+#endif
+
 #ifndef QCOMPILERDETECTION_H
 #define QCOMPILERDETECTION_H
 

src/corelib/global/qprocessordetection.h

@@ -39,6 +39,10 @@
 **
 ****************************************************************************/
 
+#ifndef QGLOBAL_H
+# include <QtCore/qglobal.h>
+#endif
+
 #ifndef QPROCESSORDETECTION_H
 #define QPROCESSORDETECTION_H
 

src/corelib/global/qsystemdetection.h

@@ -39,6 +39,10 @@
 **
 ****************************************************************************/
 
+#ifndef QGLOBAL_H
+# include <QtCore/qglobal.h>
+#endif
+
 #ifndef QSYSTEMDETECTION_H
 #define QSYSTEMDETECTION_H