flux-restore: use optparse_get_size() for --size-limit

Problem: The flux-restore(1) --size-limit=N option takes an argument
in bytes, but this can be cumbersome for larger values.

Use optparse_get_size_int() for the --size-limit option so that any
of 'k', 'K', 'M', or 'G' for value < 2G can be used as an argument to
this option.

Author: grondo

src/cmd/builtin/restore.c

@@ -366,7 +366,7 @@ static int cmd_restore (optparse_t *p, int ac, char *av[])
         content_flags |= CONTENT_FLAG_CACHE_BYPASS;
         kvs_checkpoint_flags |= KVS_CHECKPOINT_FLAG_CACHE_BYPASS;
     }
-    blob_size_limit = optparse_get_int (p, "size-limit", 0);
+    blob_size_limit = optparse_get_size_int (p, "size-limit", "0");
 
     h = builtin_get_flux_handle (p);
     ar = restore_create (infile);