Use --symlink-type=sys for Cygwin setup

Cygwin setup 2.912 has a bug in native Windows symlink support and
writes some corrupt symlinks; in particular /etc/ssl/certs is corrupt
which breaks git and curl.

Depexts will still install using native Windows symlinks, but this
should hopefully be less of an issue as the bug affects absolute
symlinks, which are less common outside of the base packages.

Author: dra27

CHANGELOG.md

@@ -12,6 +12,9 @@ and this project adheres to
 
 - Fallback to the version in which the assets exist if no assets exist in the
   latest opam release.
+- Instruct Cygwin setup to use "sys" symlinks during setup (partial workaround
+  for bug with native symlinks in Cygwin setup - some depexts may still be
+  affected)
 
 ## [2.0.0-beta11]
 

dist/index.js

@@ -202,6 +202,7 @@ async function setupCygwin() {
     site,
     "--packages",
     packages,
+    "--symlink-type=sys",
   ]);
   const setupExePath = await io.which("setup-x86_64.exe");
   await io.cp(setupExePath, CYGWIN_ROOT);