Anything that calls `xcodebuild` needs a full install of XCode.app. Two
formulae ommitted from this patch:
- `fuse4x_kext`: Everything that depends on the kernel extension can be
compiled by the CLT. Therefore, this formula is bottled and XCode is only
needed to produce the bottles.
- `graphviz`: XCode is only used to create GraphViz.app which is not used by
any of the things which depend on `graphviz`. Creating the app should be
made into an option.
The compiler setting in the xcodeproj is overridden by the CC setting in the environment. This is a bit insane IMO since the xcodeproj itself has detailed decisions about what tools to use.
FixesHomebrew/homebrew#6406.
