testutil: ensure good treatment of argv on non-Unix platforms

From a Unix point of view, some other platform families have certain
quirks.  Windows command prompt doesn't expand globs into actual file
names, so we must do this.  VMS has some oddity with argv pointer size
that can cause crashes if you're not careful (by copying it to a less
surprising pointer size array).

The fixups already exist and are used in the apps/ code.  However, the
testutil code started using the opt routines from apps/ without
including the non-Unix fixups.  This change fixes that.

For VMS' sake, libtestutil gets an app_malloc() shim, to avoid sucking
in all of apps/apps.c.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8381)