Include Win10 user symlink support at next libuv bump

[ihnorton]

Recent Win 10 updates permit unprivileged users to create symlinks, much like a proper OS.

Currently Julia returns permission denied on such symlinks (tested in Fall Creators Update), because the libuv fork does not correctly handle the applicable reparse points. Doing so will require backporting at least the following upstream change:

libuv/libuv#1466

(x-ref #24483 which also involves reparse point support)

[musm]

I think we already include the patch on our version of libuv

[musm]

@ihnorton please re-open if not, but I'm almost certain it is.