Fix VIT/INT from status changes not benefiting from bMaxHPrate/bMaxSP…

[MrKeiKun]

Pull Request Prelude

• I have followed proper Hercules code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

VIT/INT granted by equipment and VIT/INT granted by status changes (e.g. SC_FOOD_VIT, SC_FOOD_INT_CASH) were going through different code paths when recalculating MaxHP/MaxSP, causing them to be worth different amounts of HP/SP
whenever bMaxHPrate/bMaxSPrate (or battle_config.hp_rate/sp_rate) was non-default:

• status_calc_pc_() computes the VIT-based HP, adds flat bonuses, then multiplies the whole thing by sd->hprate and battle_config.hp_rate. This path only sees equipment VIT, since it runs "from scratch, without SC
  adjustments."
• status_calc_bl_main()'s SCB_MAXHP handler recomputes the VIT-based HP using the SC-inclusive VIT, but instead of re-applying the same rate, it just added the delta between the previously-computed, already-rated bst->max_hp and the previously-computed, unrated sd->status.max_hp. That delta bakes in the rate for the equipment-VIT portion only, so any VIT contributed by a status change was added at 1x regardless of bMaxHPrate.

Note: this does not address the separate concern raised in the same issue about SC-based %MaxHP bonuses (SC_FORCEOFVANGUARD, SC_RAISINGDRAGON, SC_EPICLESIS, etc.) stacking multiplicatively rather than additively, Probably in another PR that will be fixed as I need to investigate for it further.

Issues addressed: #914