Use copy_file_range(2) only on Linux >= 5.3

[kubo39]

In case copy_file_rang(2), Linux's man page says:

A major rework of the kernel implementation occurred in 5.3.
Areas of the API that weren't clearly defined were clarified and
the API bounds are much more strictly checked than on earlier
kernels. Applications should target the behaviour and
requirements of 5.3 kernels.
First support for cross-filesystem copies was introduced in Linux
5.3. Older kernels will return -EXDEV when cross-filesystem
copies are attempted.

And at least Go's Issue shows that it's broken in CIFS.
I think it should be fixed like Go did.

[the8472]

Is that issue not covered by the workaround in #75428?

[kubo39]

Ahh, sorry I should've looked into more deeply. I think this is covered by #75428 so close.