remove the write-only second animation sound field

loplugin:unusedfields already lists it as only used in the constructor.
Drop it, and note in its place that the second effect's sound URL really
lives in the shape's bookmark string, not in a sound field of its own.

Signed-off-by: Caolán McNamara <caolan.mcnamara@collabora.com>
Change-Id: I6ba402fd6e8052d6533f396d746da735abbf27bd
Reviewed-on: https://gerrit.collaboraoffice.com/c/online/+/4809
Tested-by: Jenkins CPCI <releng@collaboraoffice.com>
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
(cherry picked from commit 9d96470a60ad0c783fd3836bfc7f22ea91c5c24a)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/207282
Tested-by: Jenkins
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

compilerplugins/clang/unusedfields.only-used-in-constructor.results

@@ -544,8 +544,6 @@ sccomp/source/solver/ParticelSwarmOptimization.hxx:55
     ParticleSwarmOptimizationAlgorithm maRandomDevice std::random_device
 scripting/source/stringresource/stringresource.cxx:1246
     stringresource::(anonymous namespace)::BinaryInput m_aData Sequence<sal_Int8>
-sd/inc/anminfo.hxx:51
-    SdAnimationInfo maSecondSoundFile OUString
 sd/qa/inc/sdtiledrenderingtest.hxx:79
     SdTestViewCallback m_callbackWrapper TestLokCallbackWrapper
 sd/qa/unit/tiledrendering/tiledrendering.cxx:2830

sd/inc/anminfo.hxx

@@ -48,7 +48,9 @@ public:
     css::presentation::ClickAction     meClickAction;  ///< Action at mouse click
     css::presentation::AnimationEffect meSecondEffect; ///< for object fading.
     css::presentation::AnimationSpeed  meSecondSpeed;  ///< for object fading.
-    OUString                    maSecondSoundFile; ///< for object fading.
+    // The second (object-fade) effect has no sound-file field of its own.
+    // When mbSecondSoundOn is set, its sound URL is the shape's bookmark
+    // string, set and read through SetBookmark and GetBookmark.
     bool                        mbSecondSoundOn;   ///< for object fading.
     bool                        mbSecondPlayFull;  ///< for object fading.
     sal_uInt16                  mnVerb;            ///< for OLE object

sd/source/core/anminfo.cxx

@@ -68,7 +68,6 @@ SdAnimationInfo::SdAnimationInfo(const SdAnimationInfo& rAnmInfo, SdrObject& rOb
                  meClickAction              (rAnmInfo.meClickAction),
                  meSecondEffect             (rAnmInfo.meSecondEffect),
                  meSecondSpeed              (rAnmInfo.meSecondSpeed),
-                 maSecondSoundFile          (rAnmInfo.maSecondSoundFile),
                  mbSecondSoundOn            (rAnmInfo.mbSecondSoundOn),
                  mbSecondPlayFull           (rAnmInfo.mbSecondPlayFull),
                  mnVerb                     (rAnmInfo.mnVerb),