centralize and fixup example sources install targets

This follows suit with aeb036e in qtbase.

Change-Id: Ie8580d0a1f38ab9858b0e44c9f99bdc552a1752a
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: hjk <qthjk@ovi.com>

examples/multimedia/audioengine/qml/audioengine.qmlproject

@@ -0,0 +1,16 @@
+import QmlProject 1.1
+
+Project {
+    mainFile: "audioengine.qml"
+
+    /* Include .qml, .js, and image files from current directory and subdirectories */
+    QmlFiles {
+        directory: "."
+    }
+    JavaScriptFiles {
+        directory: "."
+    }
+    ImageFiles {
+        directory: "."
+    }
+}