avcodec/alsdec: propagate read_diff_float_data() errors in read_frame_data()

The return value of read_diff_float_data() was previously ignored,
allowing decode to continue silently with partially transformed samples
on malformed floating ALS input. Check and propagate the error.

All failure paths in read_diff_float_data() already return
AVERROR_INVALIDDATA, so the caller fix is sufficient without
any normalization inside the function.

Signed-off-by: Priyanshu Thapliyal <priyanshuthapliyal2005@gmail.com>
(cherry picked from commit febc82690d)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/alsdec.c

@@ -1773,7 +1773,9 @@ static int read_frame_data(ALSDecContext *ctx, unsigned int ra_frame)
     }
 
     if (sconf->floating) {
-        read_diff_float_data(ctx, ra_frame);
+        ret = read_diff_float_data(ctx, ra_frame);
+        if (ret < 0)
+            return ret;
     }
 
     if (get_bits_left(gb) < 0) {