[CMake] Declare cmake_minimum_required() unconditionally.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@202235 91177308-0d34-0410-b5e6-96231b3b80d8
lldReaderWriter: move LLVM_LINK_COMPONENTS. It seems Subdirectories don't depend on LLVMObject.

Please give LLVMObject explicitly in each subdirectory if any of subdirectories required it.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@202236 91177308-0d34-0410-b5e6-96231b3b80d8