FIX: removed minor obsolete comment.
FIX: very minor code improvement.
FEAT: added new system/stack/align feature.
FIX: [ARM] extra arguments stack size calculation for [custom] calls was missing a stack-width scaling factor.

System/stack/align ensures that native stack is properly aligned at the point of calling, according to target ABI requirements. It returns the new stack pointer as pointer! [integer!].