Remove GStreamer import functionality

- Remove `src/import/ImportGStreamer.cpp`
- Remove CMake definition from `src/audacity_config.h.in`
- Remove credit in About Dialog, since we don't even bundle that anymore
- Remove GStreamer mention from comment
- Remove USE_GSTREAMER macro

The feature itself is a leftover that is more than a decade old. Upstream
Audacity and downstream packagers don't enable that either.

Signed-off-by: Panagiotis Vasilopoulos <hello@alwayslivid.com>

audacity.dox.in

@@ -2073,8 +2073,7 @@ PREDEFINED             = AUDACITY_DLL_API \
                          USE_LIBVORBIS=1 \
                          USE_LIBMAD=1 \
                          USE_LIBFLAC=1 \
-                         USE_SBSMS=1 \
-                         USE_GSTREAMER
+                         USE_SBSMS=1 
 
 # If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this
 # tag can be used to specify a list of macro names that should be expanded. The

src/AboutDialog.cpp

@@ -228,9 +228,6 @@ void AboutDialog::CreateInformationTab(ShuttleGui& AboutDialogGUI) {
     #ifndef USE_FFMPEG
     #define USE_FFMPEG 0
     #endif
-    #ifndef USE_GSTREAMER
-    #define USE_GSTREAMER 0
-    #endif
     #ifndef USE_NYQUIST
     #define USE_NYQUIST 0
     #endif
@@ -266,7 +263,6 @@ void AboutDialog::CreateInformationTab(ShuttleGui& AboutDialogGUI) {
     const auto buildInfo_libtwolame = XO("MP2 export");
     const auto buildInfo_libquicktime = XO("Import via QuickTime");
     const auto buildInfo_libffmpeg = XO("FFmpeg Import/Export");
-    const auto buildInfo_libgstreamer = XO("Import via GStreamer");
     const auto buildInfo_pluginSupport = XO("Plug-in support");
     const auto buildInfo_soundCardMixerSupport = XO("Sound card mixer support");
     const auto buildInfo_pitchTempoSupport = XO("Pitch and Tempo Change support");
@@ -295,9 +291,6 @@ void AboutDialog::CreateInformationTab(ShuttleGui& AboutDialogGUI) {
     #ifdef USE_FFMPEG
         AddBuildInfoRow(&informationStr, wxT("ffmpeg"), buildInfo_libffmpeg, USE_FFMPEG ? enabled : disabled);
     #endif
-    #ifdef USE_GSTREAMER
-        AddBuildInfoRow(&informationStr, wxT("gstreamer"), buildInfo_libgstreamer, USE_GSTREAMER ? enabled : disabled);
-    #endif
     informationStr << wxT("</table>\n");  //end table of file formats supported
 
     informationStr

src/CMakeLists.txt

@@ -659,10 +659,6 @@ list( APPEND SOURCES
          import/ImportFLAC.cpp
       >
 
-      $<$<BOOL:${USE_GSTREAMER}>:
-         import/ImportGStreamer.cpp
-      >
-
       $<$<BOOL:${USE_MIDI}>:
          import/ImportMIDI.cpp
          import/ImportMIDI.h

src/audacity_config.h.in

@@ -48,9 +48,6 @@
    */
 #cmakedefine USE_FFMPEG 1
 
-/* Define if GStreamer 1 is present */
-#cmakedefine USE_GSTREAMER 1
-
 /* Define if LADSPA plug-ins are enabled */
 #cmakedefine USE_LADSPA 1
 

src/import/Import.cpp

@@ -139,7 +139,7 @@ bool Importer::Initialize()
    static OrderingPreferenceInitializer init{
       PathStart,
       { {wxT(""), wxT("AUP,PCM,OGG,FLAC,MP3,LOF,FFmpeg") } }
-      // QT and GStreamer are only conditionally compiled and would get
+      // QT is only conditionally compiled and would get
       // placed at the end if present
    };