This commit uses parameter packs to sink `debug_item()` construction
into the `debug_info()`-specific `add()` overload. This makes the stack
space use sub-linear in typical case rather than linear (which is still
the worst case). Oddly, the stack slots that get allocated now are all
for the `0` literal for `lsb_offset`. This could be fixed by allocating
numbers statically but the existing reduction in stack use of ~98% for
a representative example (Minerva SoC) should be enough.
6e003e1af6