avcodec/wmalosslessdec: Check remaining space before padding and channel residue

Fixes: Timeout (1101sec -> 0.4sec)
Fixes: 24491/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMALOSSLESS_fuzzer-5725337036783616

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/wmalosslessdec.c

@@ -932,6 +932,8 @@ static int decode_subframe(WmallDecodeCtx *s)
             s->do_lpc = 0;
     }
 
+    if (get_bits_left(&s->gb) < 1)
+        return AVERROR_INVALIDDATA;
 
     if (get_bits1(&s->gb))
         padding_zeroes = get_bits(&s->gb, 5);