value (intmax_t) and boolean (int).
Based on that provide three functions:
- gctl_get_ascii()
- gctl_get_int()
- gctl_get_intmax()
- Hide gctl_get_param() function, as it is only used internally in
subr.c.
- Allow to provide argument name as (fmt, ...).
- Assert geom(8) bugs (missing argument is a geom(8) bug).
- Clean-up and simplify the code by using new functions and assumtions
(no more checking for missing argument).
Tested by: regression tests
f13942a746