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

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

Original commit message: "
  Original commit message: "
    Original commit message: "
       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.
       "

       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.
    "

    Additionally, this patch defines a custom exception type and thus avoids the
    requirement to include header <exception>, making it easier to deploy across
    systems without standard location of the c++ headers.
  "

  This patch also works around PR49692 and finds a way to use llvm::consumeError
  in rtti mode.
"

This patch also checks if stl is built with rtti.

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