Reopen DB in crash test

Summary:
Why don't we automatically reopen DB when running crash test (running in our nightly build)? If I understand correctly, crashtest is manually reopenning the DB, but then the DB does not check its consistency when you kill db_stress process and then re-run it again.
Does this make sense?

Test Plan: not reall

Reviewers: dhruba, haobo, emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16167

tools/db_crashtest.py

@@ -70,7 +70,7 @@ def main(argv):
             --threads=%s
             --write_buffer_size=%s
             --destroy_db_initially=0
-            --reopen=0
+            --reopen=20
             --readpercent=45
             --prefixpercent=5
             --writepercent=35

tools/db_crashtest2.py

@@ -84,7 +84,7 @@ def main(argv):
             --threads=%s
             --write_buffer_size=%s
             --destroy_db_initially=0
-            --reopen=0
+            --reopen=20
             --readpercent=45
             --prefixpercent=5
             --writepercent=35