[m-rev.] for review: Make mmc --make account for source files disappearing.

[Julien Fischer]

On Wed, 2 Apr 2014, Peter Wang wrote:

> For the master branch.
> ---
>
> mmc --make prints a grave error message when the source file of a module
> can no longer be found:
>
> ** Module `foo' is imported or included by module `bar'.
> ** dependencies for `Mercury/int3s/foo.int3' do not exist: foo.m
> ** This indicates a bug in `mmc --make'.
>
> compiler/make.module_dep_file.m:
>    	Check that the source file of a local `.module_dep' file still
>    	exists.  If it doesn't, delete the `.module_dep' file and ignore
>    	the information it contains.

That looks fine.

Cheers,
Julien.