Reverting "CMake: Don't include tools, unittets, or examples as

available targets unless LLVM_INCLUDE_X is ON. LLVM_BUILD_X implies
LLVM_INCLUDE_X"

It breaks the configuration phase when cmake is invoked without
parameters, it is too complex for the purpose and introduces an
incovenience for the user (as both LLVM_BUILD_X and LLVM_INCLUDE_X
must set to OFF for not including X on the build)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114795 91177308-0d34-0410-b5e6-96231b3b80d8