[PATCH 1/3] Define _LARGEFILE64_SOURCE for musl libc

[Reagan Bohan]

Hi Kamil,

> Why only in these two files? Maybe better place whould be to
> detect musl libc compilation and add it into meson define?

Yes, I agree adding it to meson.build is a better approach, but I think
doing so without a check for musl libc is best, because:
a) musl developers have a policy against having an easy way of checking
for musl libc - https://openwall.com/lists/musl/2013/03/29/13
b) AFAICT, there should be no affect on glibc, and all tests still pass.

Thanks,
Reagan