-device: create qdevice.pri only when build tree is initialized

The build tree is not initialized when -help is passed to configure.
The mkspecs/ directory is not created and thus the mv fails results
with the following error:
mv: cannot move `.device.vars' to `/tmp/qtbase/mkspecs/qdevice.pri': No such file or directory

The solution is to create qdevice.pri just before we run config.tests.

Change-Id: Ie83018e27a03bb840d213aae8c963b0074e62bb4
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

configure

@@ -2428,15 +2428,6 @@ if [ "$CFG_RTOS_ENABLED" = "no" ]; then
     esac
 fi
 
-#-------------------------------------------------------------------------------
-# write out device config before we run the test.
-#-------------------------------------------------------------------------------
-if cmp -s "$DEVICE_VARS_FILE" "$outpath/mkspecs/qdevice.pri"; then
-    rm -f "$DEVICE_VARS_FILE"
-else
-    mv -f $DEVICE_VARS_FILE "$outpath/mkspecs/qdevice.pri"
-fi
-
 #-------------------------------------------------------------------------------
 # tests that don't need qmake (must be run before displaying help)
 #-------------------------------------------------------------------------------
@@ -3661,6 +3652,15 @@ if [ -z "$PKG_CONFIG" ]; then
     QT_CONFIG="$QT_CONFIG no-pkg-config"
 fi
 
+#-------------------------------------------------------------------------------
+# write out device config before we run the test.
+#-------------------------------------------------------------------------------
+if cmp -s "$DEVICE_VARS_FILE" "$outpath/mkspecs/qdevice.pri"; then
+    rm -f "$DEVICE_VARS_FILE"
+else
+    mv -f $DEVICE_VARS_FILE "$outpath/mkspecs/qdevice.pri"
+fi
+
 #-------------------------------------------------------------------------------
 # tests that need qmake
 #-------------------------------------------------------------------------------