phonon: Improve chances of finding libvlc.so.*

Search the install library path as well as the hard coded /usr/lib
and /usr/local/lib (this is particularly important on system that
use the 64 suffix on x86_64.
(cherry picked from commit 47ffd252b036e4047054e3926ba0a9f94170c35e)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

bindings/phonon/CMakeLists.txt

@@ -197,6 +197,7 @@ set(INSTALL_TARGETS_DEFAULT_ARGS  RUNTIME DESTINATION "${BIN_INSTALL_DIR}"
                                   LIBRARY DESTINATION "${LIB_INSTALL_DIR}"
                                   ARCHIVE DESTINATION "${LIB_INSTALL_DIR}" COMPONENT Devel )
 
+add_definitions(-DPHONON_LIB_INSTALL_DIR="${LIB_INSTALL_DIR}")
 # on the Mac support an extra install directory for application bundles
 if(APPLE)
    set(INSTALL_TARGETS_DEFAULT_ARGS  ${INSTALL_TARGETS_DEFAULT_ARGS}

bindings/phonon/vlc/vlcloader.cpp

@@ -140,7 +140,7 @@ static QStringList findAllLibVlc()
 #if defined(Q_OS_UNIX)
     paths = QString::fromLatin1(qgetenv("LD_LIBRARY_PATH"))
             .split(QLatin1Char(':'), QString::SkipEmptyParts);
-    paths << QLatin1String("/usr/lib") << QLatin1String("/usr/local/lib");
+    paths << QLatin1String(PHONON_LIB_INSTALL_DIR) << QLatin1String("/usr/lib") << QLatin1String("/usr/local/lib");
 
     QStringList foundVlcs;
     foreach (const QString &path, paths) {