Add grading system.

[pintos-anon] / src / tests / vm / Rubric.robustness

Robustness of virtual memory subsystem:

- Test robustness of page table support.

2       pt-bad-addr
3       pt-bad-read
2       pt-write-code
3       pt-write-code2
4       pt-grow-bad

- Test robustness of "mmap" system call.

1       mmap-bad-fd
1       mmap-inherit
1       mmap-null
1       mmap-zero

2       mmap-misalign

2       mmap-over-code
2       mmap-over-data
2       mmap-over-stk
2       mmap-overlap