Revert "build: restructure CoreFoundation build rules"

[aschwaighofer]

This reverts commit e8fca9a.

Looks like this commit has broken the linux builders.

Reverts #2457

[aschwaighofer]

@swift-ci Please test

[aschwaighofer]

@compnerd @shahmishal I am going to commit this revert to get the bots blue but do we need do fix the bots configurations to make this work?

[compnerd]

@aschwaighofer - can you share any information on the failure? This went through the regular testing. The build-script is building a newer CMake at this point, so we should have the necessary CMake available.

[aschwaighofer]

@compnerd Here are some bots that failed:

https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-14_04/8014/
https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-16_04/10151/

I suspect the bots don't use update-checkout.

[compnerd]

@shahmishal - could you verify if the 14.04 and 16.04 bots use build-script/update-checkout? It seems that they aren't. As it is, these bots are no longer capable of building master-next so perhaps it is time to either retire the 14.04 and 16.04 bots or start bootstrapping more tools there. (CC: @xiaobai)

[shahmishal]

@compnerd This is failing because I need to update the Linux bots to start checking out CMake, we don't use update-checkout in regular job because we don't get change log. Jenkins only provides change log if we use Git plug-in.

I will update the jobs later today, and I cane merge this PR once it's updated.