[m-dev.] accepting "any" as "ground" for non-solver types

[Zoltan Somogyi]

Since a commit in 2003 (whose log message is attached), we have
been accepting "any" insts on non-solver types as being "ground".
I am just finishing a change that passes the actual type of the variable
being tested for groundness to inst_is_ground, and this ancient rule
causes a minor problem. The symptom is a missing error message
for tests/invalid/bad_fact_table_decls. The message in question
is the one that complains about mode "ia", i.e. input-any, as not
being acceptable in a fact table.

The underlying reason lies the call chain from code of inst_is_ground_mt_2
to maybe_any_to_bound, to type_may_contain_solver_type.
In the absence of valid type info, the type being passed here
was a type var, for which the conservative answer to "may this contain
a solver type" was yes. This caused "ia" to NOT be treated as a non-solver
type, so it was not considered ground. But when you pass the *actual* type
of the argument, an integer, type_may_contain_a_solver_type fails,
and the any *is* considered to be ground, and thus you get no error message.

This is quite unintuitive behavior. The log messages says that this behavior
is required to support HAL, but of course HAL is long dead. Is there any
*current* reason to retain this behavior? If not, I would very much like to
get rid of it.

Zoltan.
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