fix,temp: add "/tmp";
fix,temp: increase nprocs to 512;
feat: print more  info on panic;

fix,temp: increase ustack size;
feat: provide more info on panic

but cannot pass libctest pthread_cancel etc.

feat: add madvise,mremap,mlock/unlock stub

(cherry picked from commit 13990e28abd02a4db3579e3a84f80aa813c9285a)

temp: add some debug outputs

time-test runs too long!

temp: writeback consistency is ambiguous, since fat has its own cache

fix: head/tail moving;
fix: sendFile keep up with read() update

feat: add condition_variable;
refactor: File::read use given buf;
bug: exit too early

temp: use naive lru for vmo cache;
busybox run much faster now

temp: add some stats for debugging

can run many testcases now