lib/zlib: fix DFLTCC ignoring flush modes when avail_in == 0

This commit is based on:
  zlib-ng/zlib-ng@40acb3f

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mikhail Zaslonko <[email protected]>
Acked-by: Ilya Leoshkevich <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: mzaslonk

lib/zlib_dfltcc/dfltcc_deflate.c

@@ -142,7 +142,8 @@ int dfltcc_deflate(
         /* Clear history. */
         if (flush == Z_FULL_FLUSH)
             param->hl = 0;
-        *result = need_more;
+        /* Trigger block post-processing if necessary. */
+        *result = no_flush ? need_more : block_done;
         return 1;
     }