Android CI: Fix up //packages/react-native-codegen:setup_cli src copy issue

Summary:
This fixed bad src copy for Buck-building: `//packages/react-native-codegen:setup_cli`. Using rsync -L will correctly copy file contents instead of preserving symlinks (which confused yarn).

Changelog: [Internal]

Reviewed By: hramos

Differential Revision: D24577333

fbshipit-source-id: 4f586ba95d2d95d6ce8e3389e355cfb1a9121745

packages/react-native-codegen/DEFS.bzl

@@ -77,7 +77,7 @@ def rn_codegen_cli():
             bash = r"""
                 set -euo pipefail
                 mkdir -p "$OUT"
-                cp -r "$SRCDIR/." "$OUT/"
+                rsync -rLptgoD "$SRCDIR/" "$OUT"
                 cd "$OUT"
                 yarn install 2> >(grep -v '^warning' 1>&2)
                 yarn run build