Fix qbs build with Qt that does not have the SVG module.

This now works the same way as with qmake.

Change-Id: I8e6b7f32ffff19e6f4fe9d83ffe804984e33f298
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>

src/plugins/imageviewer/imageviewer.qbs

@@ -3,11 +3,17 @@ import qbs 1.0
 QtcPlugin {
     name: "ImageViewer"
 
-    Depends { name: "Qt"; submodules: ["widgets", "svg"] }
+    Depends { name: "Qt.svg"; required: false }
+    Depends { name: "Qt.widgets" }
     Depends { name: "Utils" }
 
     Depends { name: "Core" }
 
+    Properties {
+        condition: !Qt.svg.present
+        cpp.defines: base.concat("QT_NO_SVG")
+    }
+
     files: [
         "imageview.cpp",
         "imageview.h",