cmake: When using LLVM_DISTRIBUTION_COMPONENTS, adjust LLVMExports accordingly

This Makes sure we only export targets that we're distributing, since
cmake will fail to import the file otherwise due to missing targets.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286024 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed