Initial set of Makefiles

This provides support for the autoconfing & make build style.
The format, style and implementation follows that used within the llvm and clang projects.

TODO: implement out-of-source documentation builds.



git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@210177 91177308-0d34-0410-b5e6-96231b3b80d8