rar: Fix Visual Studio compiler warning

[stoeckmann]

Fixes the following warning:

warning C4244: '=': conversion from 'int64_t' to 'size_t', possible loss of data

[stoeckmann]

Although this diff looks simple, I'm not sure if the implications here aren't hiding a bug now. Actually this is eventually casted to uint32_t on all systems, yet it's a 64 bit value. Not sure if all systems truncate huge values here...

[stoeckmann]

Reviewed the changes again. It seems safe, because the values eventually come from variables of casted type. I don't mind if someone checks again though. The casts from uint64_t to size_t and back again could be interesting, but definitely out of scope of this PR which is about fixing warnings.

[LukeSkyD]

Hi thank you for your work!
Im having a similar problem compiling from the source with msvc, i created a pull request which should fix my specific issue but i dont know if it would be safe, sorry can i ask for your help?

#2209

EDIT: sorry it was late last night and didn't see this pr still had to be merged. your commit already tackles the issue.

[stoeckmann]

Any news on this one or the other PRs? Is there something I can do to support reviews?

[LukeSkyD]

Any news on this one or the other PRs? Is there something I can do to support reviews?

Yours commit/e0fb6da967f30c398955a364430fa5355c92bdd1 seems to be the most correct solution!