Fix bug where double syncs not inserted when using -i -p 1.

Decompression can be started at an independent block, requested
with -i or --independent, where such blocks are marked in the
output with double sync markers. This fixes a bug where only
single markers were emitted when a single processor (-p 1) was
used in combination with independent blocks.

pigz.c

@@ -2399,10 +2399,9 @@ local void single_compress(int reset) {
                     }
                 }
                 else
-#else
-                {
                     DEFLATE_WRITE(Z_SYNC_FLUSH);
-                }
+#else
+                DEFLATE_WRITE(Z_SYNC_FLUSH);
 #endif
                 if (!g.setdict)             // two markers when independent
                     DEFLATE_WRITE(Z_FULL_FLUSH);