[m-rev.] for review: implement --warn-stdlib-shadowing, part 2

[Julien Fischer]

On Fri, 7 Jan 2022, Zoltan Somogyi wrote:

> Implement --warn-sdtlib-shadowing.
> 
> compiler/mercury_compile_main.m:
>     I added that option a week or so ago, but at that time, it did nothing.
>     This diff implements the warning.
> 
> library/LIB_FLAGS.in:
>     Disable the warning for the modules in the library directory.
> 
> configure.ac:
>     Require the installed compiler to recognize the option, since without this,
>     library/LIBFLAGS won't work.
> 
> tests/warnings/profiling_builtin.{m,exp}:
> tests/warnings/time.{m,exp}:
> tests/warnings/time.subtime.m:
>     Two test cases for the warning. One, time, shadows the name of
>     a documented library module, the other, profiling_builtin,
>     shadows the name an un documented library module.

s/un documented/undocumented/

What's the subtime module testing for?

The diff is fine otherwise.

Julien.