Reland "[clang-repl] Re-implement clang-interpreter as a test case."

Original commit message:"
  The current infrastructure in lib/Interpreter has a tool, clang-repl, very
  similar to clang-interpreter which also allows incremental compilation.

  This patch moves clang-interpreter as a test case and drops it as conditionally
  built example as we already have clang-repl in place.

  Differential revision: https://reviews.llvm.org/D107049
"

This patch also ignores ppc due to missing weak symbol for __gxx_personality_v0
which may be a feature request for the jit infrastructure. Also, adds a missing
build system dependency to the orc jit.