avformat/lrcdec: Fix fate-sub-lrc-ms-remux on x86-32

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 0243cf89b137b093b02a5c61a76e28cec1d69ae9)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/lrcdec.c

@@ -91,7 +91,7 @@ static int64_t read_ts(const char *p, int64_t *start)
     if (ret != 3 || prefix[0] != '[' || ss < 0 || ss > 60) {
         return 0;
     }
-    *start = (mm * 60 + ss) * AV_TIME_BASE;
+    *start = llrint((mm * 60 + ss) * AV_TIME_BASE);
     if (prefix[1] == '-') {
         *start = - *start;
     }