Fix compile issue with ZSTD_LEGACY_SUPPORT=1 and ZSTD_HEAPMODE=0

lib/legacy/zstd_v04.c

@@ -4037,7 +4037,7 @@ size_t ZSTDv04_decompress(void* dst, size_t maxDstSize, const void* src, size_t
     return regenSize;
 #else
     ZSTD_DCtx dctx;
-    return ZSTD_decompressDCtx(&dctx, dst, maxDstSize, src, srcSize);
+    return ZSTDv04_decompressDCtx(&dctx, dst, maxDstSize, src, srcSize);
 #endif
 }