flv: Improve log messages

Messages should start with a capital letter and possibly end with a "."
if they are statements.

libavformat/flvdec.c

@@ -565,7 +565,7 @@ static int flv_read_header(AVFormatContext *s)
         flags = FLV_HEADER_FLAG_HASVIDEO | FLV_HEADER_FLAG_HASAUDIO;
         av_log(s, AV_LOG_WARNING,
                "Broken FLV file, which says no streams present, "
-               "this might fail\n");
+               "this might fail.\n");
     }
 
     s->ctx_flags |= AVFMTCTX_NOHEADER;
@@ -798,7 +798,7 @@ static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
                     return flv_data_packet(s, pkt, dts, next);
                 } else /* skip packet */
                     av_log(s, AV_LOG_DEBUG,
-                           "skipping flv packet: type %d, size %d, flags %d\n",
+                           "Skipping flv packet: type %d, size %d, flags %d.\n",
                            type, size, flags);
 
 skip:
@@ -899,7 +899,7 @@ skip:
             if (cts < 0) { // dts are wrong
                 flv->wrong_dts = 1;
                 av_log(s, AV_LOG_WARNING,
-                       "negative cts, previous timestamps might be wrong\n");
+                       "Negative cts, previous timestamps might be wrong.\n");
             }
             if (flv->wrong_dts)
                 dts = AV_NOPTS_VALUE;