Merge #21272: guix: Passthrough SDK_PATH into container
13a9fd11a507fd3398bc2c0a0575bdc81579243f guix: Passthrough SDK_PATH into container (Carl Dong)
Pull request description:
This is a usability improvement for Guix builders so that they don't have to extract the Xcode tarball into `depends/SDKs` every time.
ACKs for top commit:
Tested ACK 13a9fd11a507fd3398bc2c0a0575bdc81579243f