tools: libxc: restore: copy the correct page to memory

tools: libxc: restore: copy the correct page to memory

apply_batch() only handles MAX_BATCH_SIZE pages at one time. If
there is some bogus/unmapped/allocate-only/broken page, we will
skip it. So when we call apply_batch() again, the first page's
index is curbatch - invalid_pages. invalid_pages stores the number
of bogus/unmapped/allocate-only/broken pages we have found.

In many cases, invalid_pages is 0, so we don't catch this error.

Signed-off-by: Hong Tao <bobby.hong@huawei.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>