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/spectrum/doc/src/spectrum.qdoc

@@ -0,0 +1,64 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file.  Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: http://www.gnu.org/copyleft/fdl.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+    \example spectrum
+    \title Spectrum Example
+    \ingroup audio_examples
+    \brief The Spectrum Example uses a combination multimedia APIs to process microphone input.
+
+    The Spectrum Analyzer example shows how the \l{QtMultimedia Module} can be
+    used to record and then play back an audio stream.
+
+    \image spectrum-demo.png
+
+    Because QtMultimedia allows the application to access the raw audio
+    stream, the data can either be inspected or modified by the application.
+    The Spectrum Analyzer example displays three pieces of information while
+    audio is being either captured or played back:
+
+    \list
+    \li Information about the raw audio stream, shown in the uppermost widget:
+    \list
+        \li The amount of data currently in the buffer, shown in blue
+        \li The segment of data which was most recently analysed to compute
+        the frequency spectrum, shown in green
+        \li The raw audio waveform, shown in white and scrolling from right to
+        left
+    \endlist
+    \li A representation of the frequency spectrum, shown at the lower left
+    \li The current RMS level of the audio stream, and the recent 'high
+    watermark' level, shown at the lower right
+    \endlist
+
+    Spectrum analysis is performed by calculating the Fast Fourier Transform
+    (FFT) of a segment of audio data.  An open-source library,
+    \l{http://ldesoras.free.fr/prod.html}{FFTReal}, against which the
+    application is dynamically linked, is used to compute the transform.
+*/
+
+