Match types when calculating remaining in FileHandle's _readDataOfLength

[gonzalolarralde]

This was causing an error when trying to get the remaining amount of data.

[mattrajca]

Can you add a test for this?

[pushkarnk]

Per this the st_size member is also of type off_t. Am I missing something here?

[gonzalolarralde]

@mattrajca @pushkarnk sorry for the lack of context in the original message.

@pushkarnk it is true for linux, it is not for 32-bits arm or at least in bionic. This is causing a compilation error when trying to combine a long long with an off_t without casting.

@mattrajca this wasn't causing a runtime error but a compilation error under some particular circumstances (-target armv7-linux-androideabi in my case)

[parkera]

@swift-ci please test

[parkera]

Let's see if this causes a compilation error on other platforms...

[pushkarnk]

I think we can merge this. It seems to be blocking compilation of Foundation on the said platform. On platforms where st_size is of type off_t (where a cast isn't necessary), I don't think this explicit cast should cause a problem.

[pushkarnk]

@swift-ci please test and merge