Changes

Changes from Git (git https://github.com/llvm/llvm-project.git)

Commit 38778e1087b2825e91b07ce4570c70815b49dcdc by sguelton Provide anchor for compiler extensions This patch is cherry-picked from 04b0a4e22e3b4549f9d241f8a9f37eebecb62a31, and amended to prevent an undefined reference to `llvm::EnableABIBreakingChecks'
	llvm/lib/Extensions/LLVMBuild.txt
	llvm/lib/Extensions/Extensions.cpp