Use g_assert_error() and g_assert_no_error()

Use g_assert_error() and g_assert_no_error()

	* tests/data-input-stream.c:
	* tests/data-output-stream.c:
	* tests/live-g-file.c:
	* tests/memory-input-stream.c:
	* tests/memory-output-stream.c: Use g_assert_error() and
	g_assert_no_error()

svn path=/trunk/; revision=7556