refine the options

@@ -114,22 +114,17 @@ Options:
   -h, --help                print this message
   -h, --help                print this message
                           
                           
   --with-ssl                enable rtmp complex handshake, requires openssl-devel installed.
   --with-ssl                enable rtmp complex handshake, requires openssl-devel installed.
-                            to delivery h264 video and aac audio to flash player.
   --with-hls                enable hls streaming, mux RTMP to m3u8/ts files.
   --with-hls                enable hls streaming, mux RTMP to m3u8/ts files.
   --with-hds                enable hds streaming, mux RTMP to f4m/f4v files.
   --with-hds                enable hds streaming, mux RTMP to f4m/f4v files.
   --with-dvr                enable dvr, mux RTMP to flv files.
   --with-dvr                enable dvr, mux RTMP to flv files.
   --with-nginx              enable delivery HTTP stream with nginx.
   --with-nginx              enable delivery HTTP stream with nginx.
-                            build nginx at: ./objs/nginx/sbin/nginx
   --with-http-callback      enable http hooks, build cherrypy as demo api server.
   --with-http-callback      enable http hooks, build cherrypy as demo api server.
   --with-http-server        enable http server to delivery http stream.
   --with-http-server        enable http server to delivery http stream.
   --with-stream-caster      enable stream caster to serve other stream over other protocol.
   --with-stream-caster      enable stream caster to serve other stream over other protocol.
   --with-http-api           enable http api, to manage SRS by http api.
   --with-http-api           enable http api, to manage SRS by http api.
   --with-ffmpeg             enable transcoding tool ffmpeg.
   --with-ffmpeg             enable transcoding tool ffmpeg.
-                            build ffmpeg at: ./objs/ffmpeg/bin/ffmpeg
   --with-transcode          enable transcoding features.
   --with-transcode          enable transcoding features.
-                            user must specifies the transcode tools in conf.
   --with-ingest             enable ingest features.
   --with-ingest             enable ingest features.
-                            user must specifies the ingest tools in conf.
   --with-stat               enable the data statistic, for http api.
   --with-stat               enable the data statistic, for http api.
   --with-librtmp            enable srs-librtmp, library for client.
   --with-librtmp            enable srs-librtmp, library for client.
   --with-research           build the research tools.
   --with-research           build the research tools.