This is the first commit for the "Clang-based C/C++ diff tool" GSoC project.
ASTDiff is a new library that computes a structural AST diff between two ASTs
using the gumtree algorithm. Clang-diff is a new Clang tool that will show
the structural code changes between different ASTs.
Patch by Johannes Altmanninger!
Differential Revision: https://reviews.llvm.org/D34329
llvm-svn: 308731