avcodec/zmbv: remove useless zero check on dimensions

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/zmbv.c

@@ -599,13 +599,12 @@ static av_cold int decode_init(AVCodecContext *avctx)
     c->decomp_size = (avctx->width + 255) * 4 * (avctx->height + 64);
 
     /* Allocate decompression buffer */
-    if (c->decomp_size) {
-        if (!(c->decomp_buf = av_mallocz(c->decomp_size))) {
+    c->decomp_buf = av_mallocz(c->decomp_size);
+    if (!c->decomp_buf) {
         av_log(avctx, AV_LOG_ERROR,
                 "Can't allocate decompression buffer.\n");
         return AVERROR(ENOMEM);
     }
-    }
 
     c->zstream.zalloc = Z_NULL;
     c->zstream.zfree = Z_NULL;