std.fs.File.readvAll: fix behavior for 0-length vectors

The OS layer expects pointer addresses to be inside the application's
address space even if the length is zero. Meanwhile, in Zig, slices may
have undefined pointer addresses when the length is zero. So this
function now modifies the iov_base fields when the length is zero.
25c3878c00Andrew Kelley committed on 3/15/2023, 5:48:14 PMparent7db7400
2 files changedLine totals unavailable