fix qmlplugindump's import path construction

the location of the import paths have changed a long time ago.
also, we can make use of QTREPOS now.

Change-Id: Iee50854b7441968c3c60538e54d9312e53d39cb6
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

mkspecs/features/qml_plugin.prf

@@ -81,9 +81,11 @@ load(qt_common)
             qmlplugindump = qmlplugindump
         qtPrepareTool(QMLPLUGINDUMP, $$qmlplugindump)
         importpath.value =
-        for(qmod, QMAKEMODULES) {
-            qmod = $$section(qmod, /, 0, -3)/imports
-            qml1_target: qmod = $$qmod/QtDeclarative
+        for(qmod, QTREPOS) {
+            qml1_target: \
+                qmod = $$qmod/imports
+            else: \
+                qmod = $$qmod/qml
             exists($$qmod): importpath.value += $$shell_path($$qmod)
         }
         importpath.name = QML_IMPORT_PATH