* build: build squirrel and its dependencies from source
* chore: do not use fork for squirrel.mac
* build: do not ship headers with dependency frameworks
* Update BUILD.gn
* chore: s/striped/stripped
* chore: update as per feedback
* chore: use ARC and fix build errors
* chore: fix ARC Squirrel self retainer
* build: enable sccache on windows
* chore: temporarily disable the docs only check
* build: fix escaping in sccache path on windows
* Update appveyor.yml
* Update appveyor.yml
* Use sccache settings from CI
* Use Azure enabled sccache for Windows