allocate workspace on stack instead of heap (#4)

Author: stuarthicks

Diff for: lib/block.c

@@ -21,20 +21,18 @@
 int smile_decode_block(void *dst, int dstlen, void *src, int srclen)
 {
     s_stream stream;
-    stream.workspace = malloc(sizeof(struct decode_workspace));
-    smile_decode_init(&stream);
+    struct decode_workspace workspace;
+    stream.workspace = &workspace;
+    smile_decode_reset(&stream);
 
     stream.next_in = src;
     stream.avail_in = srclen;
 
     stream.next_out = dst;
     stream.avail_out = dstlen;
 
-    // Decode block
     int err = smile_decode(&stream);
 
-    free(stream.workspace);
-
     if (err == -1) {
       return -EIO;
     }