Squashed 'site_scons/' changes from 312e4f1..524ad2e

524ad2e Keep a simple link command on Darwin

git-subtree-dir: site_scons
git-subtree-split: 524ad2ef8e81279e24f440023b7ce77ac22a50cc
Merge commit '312250aefb5f4e906b9a79851ec49466258f5a09'