avfilter/vf_drawtext: fixed default/flt formatting ignoring offset parameter

Signed-off-by: Alex Agranovsky <alex@sighthound.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavfilter/vf_drawtext.c

@@ -809,7 +809,7 @@ static int func_pts(AVFilterContext *ctx, AVBPrint *bp,
         pts += (double)delta / AV_TIME_BASE;
     }
     if (!strcmp(fmt, "flt")) {
-        av_bprintf(bp, "%.6f", s->var_values[VAR_T]);
+        av_bprintf(bp, "%.6f", pts);
     } else if (!strcmp(fmt, "hms")) {
         if (isnan(pts)) {
             av_bprintf(bp, " ??:??:??.???");