resize_file() can support large file that filesize more than 4GB

[fooofei]

the api

bool resize_file(size_t target_length)

, should change to

bool resize_file(uint64_t target_length)

to support large file that filesize more than 4GB

[wjakob]

The easier solution is simply to compile with 64 bit ;)

[fooofei]

we should give the user an opportunity to compile with windows x86, so make the code stronger.