Reland "[clang-repl] Enable debugging of JIT-ed code."

Original commit message: "
[clang-repl] Enable debugging of JIT-ed code.

    This change follows llvm/llvm-project@21b5ebd and makes use of the jitlink
    infrastructure. In order to use this feature inside lldb one needs to run the
    lldb command: settings set plugin.jit-loader.gdb.enable on

    This works currently only on Darwin since jitlink is not a default ELF/x86-64
    backend yet.

    Differential revision: https://reviews.llvm.org/D148481
"

This patch reverts commit e64fbf2c and adds
the missing library dependencies which caused the initial failure.