XQuartz-2.8.1

This is an automation-friendly packaging of the XQuartz 2.8.1 release with the following modifications:

• fixes broken pkg-config chain (some .pc files were missing in the release)
• only includes the /opt/X11 subdirectory, does not mess with system settings
• adds /opt/X11/libexec/postinstall script to create X11 symlinks (last lines from the installer packaging script in the release). It is optional, supports legacy scripts that expect /usr/X11 to exist.
• adds /opt/X11/libexec/pkg-config which uses /opt/X11 prefix. It is intentionally not placed in bin such that it does not confuse any existing pkg-config installations. To make it part of XQuartz use sudo ln -s ../libexec/pkg-config /opt/X11/bin/pkg-config. If you use any other pkg-config add /opt/X11/lib/pkgconfig to PKG_CONFIG_PATH instead.

The actual XQuartz binary content is identical to the release.

Suggested installation:

curl -sSL https://github.com/R-macos/XQuartz/releases/download/XQuartz-2.8.1/XQuartz-2.8.1.tar.xz \
 | sudo tar fxj - -C / && sudo sh /opt/X11/libexec/postinstall