[m-rev.] for post-commit review: classify builtin type ctors via switch

[Julien Fischer]

Hi Zoltan,

On Wed, 27 Dec 2017, Zoltan Somogyi wrote:

> If anyone knows why classify_type_ctor treats "pred" and "func"
> in two such different ways, I would love to hear it.

One of your recent changes (most likely this one) has broken compilation
of the standard library in the csharp grade,

     Making Mercury/opts/builtin.opt
     Uncaught Mercury exception:
     Software Error: map.lookup: key not found
         Key Type: string
         Key Value: "int"
         Value Type: tree234.tree234(parse_tree.prog_data.type_ctor, hlds.hlds_data.hlds_type_defn)
     Stack dump not available in this grade.
     ** Error making `Mercury/opts/builtin.opt'.
     gmake[1]: *** [libmer_std.install] Error 1
     gmake[1]: Leaving directory
     `/mnt/opturion/jfischer/mercury-4.git/stage2/install_grade_dir.csharp/library'
     To clean up from failed install, remove
     /mnt/opturion/jfischer/mercury-4.git/stage2/install_grade_dir.csharp
    gmake: *** [install_grades] Error 1

Julien.