build tree. Now just-built Clang is used to:
1) compile instrumented sources (as before);
2) compile non-instrumented sources;
3) compile our own instrumented version of googletest;
4) link it all together using -fsanitize=address flag
(instead of trying to copy linker behavior in
CMake build rules).
This makes ASan unittests pretty much self-consistent
and independent of other LLVM libraries.
llvm-svn: 170541
