Include sendfile64() for Linux

[nroi]

sendfile uses the off_t type, which is platform dependent. On 64-bit architectures, I can pass an off64_t as the third argument to libc::sendfile, but on 32-bit architectures, this does not compile. sendfile64 on the other hand uses a 64-bit wide offset even on 32-bit architectures, so that off64_t can be used.

Excerpt from man 2 sendfile:

The original Linux sendfile() system call was not designed to handle large file offsets. Consequently, Linux 2.4 added sendfile64(), with a wider type for the offset argument.

I hope that supporting Linux versions below 2.4 is not a requirement for libc.

[rust-highfive]

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[JohnTitor]

Looks good, thanks!

I hope that supporting Linux versions below 2.4 is not a requirement for libc.

Yeah, it should be fine, I believe.

[JohnTitor]

@bors r+

[bors]

📌 Commit a8c1d97 has been approved by JohnTitor