Small enhancements for libguestfs.

1.Default timeout for virt-inspect may be not enough.
2.Include hda type driver for finding disk.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
utils_test.libguestfs: Fix path connection failure.

For guestmount path, we need to connect mountpoint with
provided path. And use abspath to remove redundant '/'.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>