[ASan] Add llvm-symbolizer from to tools/

This is the second and last (2/2) part of a change that moves llvm-symbolizer to llvm/tools/, which will allow to build it
with both cmake and configure+make.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167723 91177308-0d34-0410-b5e6-96231b3b80d8