Fix corruption_test failure caused by auto-enablement of checksum verification.

Summary:
Patch  https://reviews.facebook.net/D15591 enabled checksum
verification by default. This caused the unit test to fail.

Test Plan: ./corruption_test

Reviewers: igor, kailiu

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15795

HISTORY.md

@@ -1,5 +1,9 @@
 # Rocksdb Change Log
 
+## Unreleased
+* By default, checksums are verified on every read from database
+
+
 ## 2.7.0 (01/28/2014)
 
 ### Public API changes

db/corruption_test.cc

@@ -95,7 +95,12 @@ class CorruptionTest {
     int bad_values = 0;
     int correct = 0;
     std::string value_space;
-    Iterator* iter = db_->NewIterator(ReadOptions());
+    // Do not verify checksums. If we verify checksums then the
+    // db itself will raise errors because data is corrupted.
+    // Instead, we want the reads to be successful and this test
+    // will detect whether the appropriate corruptions have
+    // occured.
+    Iterator* iter = db_->NewIterator(ReadOptions(false, true));
     for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
       uint64_t key;
       Slice in(iter->key());