[libre-riscv-dev] bugzilla budget tracking

[Jacob Lifshay]

I added two new custom fields to help keep track of budget allocation:

parent task for budget -- the bug id that the current bug's funding comes
from -- bugzilla also automatically shows the list of child tasks

total budget of task and subtasks -- the amount allocated to a task and all
subtasks -- shouldn't change when adding new subtasks

I also edited the description for the old task budget field to clarify that
it excludes the budget allocated to subtasks.

If this was not desired, feel free to revert my changes.

Jacob