Deprecate Autoconf

As per the very positive feedback from llvm-dev (http://lists.llvm.org/pipermail/llvm-dev/2015-November/092150.html), this commit officially deprecates the LLVM autoconf-based build system.

Anyone still using it should switch to CMake.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252520 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed