Make CompactionInputErrorParanoid less flakey

Summary:
I'm getting lots of e-mails with CompactionInputErrorParanoid failing. Most recent example early morning today was: http://ci-builds.fb.com/job/rocksdb_valgrind/562/consoleFull

I'm putting a stop to these e-mails. I investigated why the test is flakey and it turns out it's because of non-determinsim of compaction scheduling. If there is a compaction after the last flush, CorruptFile will corrupt the compacted file instead of file at level 0 (as it assumes). That makes `Check(9, 9)` fail big time.

I also saw some errors with table file getting outputed to >= 1 levels instead of 0. Also fixed that.

Test Plan: Ran corruption_test 100 times without a failure. Previously it usually failed at 10th occurrence.

Reviewers: dhruba, haobo, ljin

Reviewed By: ljin

CC: leveldb

Differential Revision: https://reviews.facebook.net/D18285