stream_lavf: enable SRT protocol support through FFmpeg

Additionally, announce support for the protocol in Mac and Linux
application metadata.

TOOLS/osxbundle/mpv.app/Contents/Info.plist

@@ -217,6 +217,7 @@
           <string>ftp</string>
           <string>udp</string>
           <string>smb</string>
+          <string>srt</string>
         </array>
       </dict>
       <dict>

etc/mpv.desktop

@@ -33,4 +33,4 @@ Exec=mpv --player-operation-mode=pseudo-gui -- %U
 Terminal=false
 Categories=AudioVideo;Audio;Video;Player;TV;
 MimeType=application/ogg;application/x-ogg;application/mxf;application/sdp;application/smil;application/x-smil;application/streamingmedia;application/x-streamingmedia;application/vnd.rn-realmedia;application/vnd.rn-realmedia-vbr;audio/aac;audio/x-aac;audio/vnd.dolby.heaac.1;audio/vnd.dolby.heaac.2;audio/aiff;audio/x-aiff;audio/m4a;audio/x-m4a;application/x-extension-m4a;audio/mp1;audio/x-mp1;audio/mp2;audio/x-mp2;audio/mp3;audio/x-mp3;audio/mpeg;audio/mpeg2;audio/mpeg3;audio/mpegurl;audio/x-mpegurl;audio/mpg;audio/x-mpg;audio/rn-mpeg;audio/musepack;audio/x-musepack;audio/ogg;audio/scpls;audio/x-scpls;audio/vnd.rn-realaudio;audio/wav;audio/x-pn-wav;audio/x-pn-windows-pcm;audio/x-realaudio;audio/x-pn-realaudio;audio/x-ms-wma;audio/x-pls;audio/x-wav;video/mpeg;video/x-mpeg2;video/x-mpeg3;video/mp4v-es;video/x-m4v;video/mp4;application/x-extension-mp4;video/divx;video/vnd.divx;video/msvideo;video/x-msvideo;video/ogg;video/quicktime;video/vnd.rn-realvideo;video/x-ms-afs;video/x-ms-asf;audio/x-ms-asf;application/vnd.ms-asf;video/x-ms-wmv;video/x-ms-wmx;video/x-ms-wvxvideo;video/x-avi;video/avi;video/x-flic;video/fli;video/x-flc;video/flv;video/x-flv;video/x-theora;video/x-theora+ogg;video/x-matroska;video/mkv;audio/x-matroska;application/x-matroska;video/webm;audio/webm;audio/vorbis;audio/x-vorbis;audio/x-vorbis+ogg;video/x-ogm;video/x-ogm+ogg;application/x-ogm;application/x-ogm-audio;application/x-ogm-video;application/x-shorten;audio/x-shorten;audio/x-ape;audio/x-wavpack;audio/x-tta;audio/AMR;audio/ac3;audio/eac3;audio/amr-wb;video/mp2t;audio/flac;audio/mp4;application/x-mpegurl;video/vnd.mpegurl;application/vnd.apple.mpegurl;audio/x-pn-au;video/3gp;video/3gpp;video/3gpp2;audio/3gpp;audio/3gpp2;video/dv;audio/dv;audio/opus;audio/vnd.dts;audio/vnd.dts.hd;audio/x-adpcm;application/x-cue;audio/m3u;
-X-KDE-Protocols=ftp,http,https,mms,rtmp,rtsp,sftp,smb
+X-KDE-Protocols=ftp,http,https,mms,rtmp,rtsp,sftp,smb,srt

stream/stream_lavf.c

@@ -412,7 +412,7 @@ const stream_info_t stream_info_ffmpeg = {
   .open = open_f,
   .protocols = (const char *const[]){
      "rtmp", "rtsp", "http", "https", "mms", "mmst", "mmsh", "mmshttp", "rtp",
-     "httpproxy", "rtmpe", "rtmps", "rtmpt", "rtmpte", "rtmpts", "srtp",
+     "httpproxy", "rtmpe", "rtmps", "rtmpt", "rtmpte", "rtmpts", "srt", "srtp",
      "gopher", "data",
      NULL },
   .can_write = true,