Rename ThreadScope symbols and comments

To reflect our lack of compatibility with ThreadScope this patch renames
many of the symbols used in the runtime system and compiler.

Generally "ThreadScope" is being renamed to "Parallel Profiling" and the new
tool (NIY) should be called "the Mercury Parallelism Profiler".

    + Rename the MR_THREADSCOPE macro to MR_PARALLEL_PROFILING.  This macro
      is controlled by the threadscope grade component.
    + Rename symbols and comments in the runtime that used the term
      "threadscope" or "ts".

There are no algorithmic changes in this patch.

compiler/code_info.m:
compiler/compile_target_code.m:
compiler/dep_par_conj.m:
compiler/global_data.m:
compiler/hlds_module.m:
compiler/layout.m:
compiler/layout_out.m:
compiler/llds.m:
compiler/llds_out_file.m:
compiler/mercury_compile_llds_back_end.m:
compiler/opt_debug.m:
compiler/par_conj_gen.m:
compiler/proc_gen.m:
library/benchmarking.m:
library/par_builtin.m:
runtime/mercury_atomic_ops.h:
runtime/mercury_conf_param.h:
runtime/mercury_context.c:
runtime/mercury_context.h:
runtime/mercury_debug.c:
runtime/mercury_debug.h:
runtime/mercury_engine.c:
runtime/mercury_engine.h:
runtime/mercury_grade.h:
runtime/mercury_memory_handlers.c:
runtime/mercury_misc.h:
runtime/mercury_par_builtin.h:
runtime/mercury_par_profile.c:
runtime/mercury_par_profile.h:
runtime/mercury_thread.c:
runtime/mercury_wrapper.c:
runtime/mercury_wrapper.h:
scripts/mgnuc.in:
util/mkinit.c:
    As above.
ThreadScope changes

runtime/mercury_par_profile.c:
runtime/mercury_par_profile.h:
    Update comments in these files to describe the origin of this code and
    that it is no-longer intended to be compatible with ThreadScope.

runtime/mercury_context.c:
    Fix a bug where the incorrect C macro was used to conditionally compile
    the logging of a parallel profiling event.

library/benchmarking.m:
    Deprecate log_threadscope_message/3 in favor of the new predicate
    log_parprof_message/3.