Fix /file/measure test on macOS
The --bytes argument is Linux-only, so causes the following test failure on BSD (such as on macOS):
--- stderr --- du: illegal option -- - usage: du [-H | -L | -P] [-a | -s | -d depth] [-c] [-h | -k | -m | -g] [-x] [-I mask] [file ...] du: illegal option -- - usage: du [-H | -L | -P] [-a | -s | -d depth] [-c] [-h | -k | -m | -g] [-x] [-I mask] [file ...] ** GLib-GIO:ERROR:../gio/tests/file.c:500:test_create_delete: assertion failed (data->monitor_changed > 0): (0 > 0)
Fix that by setting BLOCKSIZE=1 in the environment, and getting the result in blocks.
Signed-off-by: Philip Withnall withnall@endlessm.com
Helps #1392