syscalls: umount01: Give a hint on failure with EBUSY

This is the last test that may fail with EBUSY due to gvfsd-trash. But
given that the umount(2) is the syscall under the test here, let's
refrain from the retrying the call on error.

This commit add at least a warning with a hint on the likely cause of
the failure.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
1 file changed