[libFuzzer]Add a test for defeating a hash sum.

Summary:
Add a test for a data followed by 4-byte hash value.
I use a slightly modified Jenkins hash function,
as described in https://en.wikipedia.org/wiki/Jenkins_hash_function

The modification is to ensure that hash(zeros) != 0.

Reviewers: kcc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12648

llvm-svn: 247076
diff --git a/llvm/lib/Fuzzer/test/fuzzer.test b/llvm/lib/Fuzzer/test/fuzzer.test
index d5bd9a3..70dbce8 100644
--- a/llvm/lib/Fuzzer/test/fuzzer.test
+++ b/llvm/lib/Fuzzer/test/fuzzer.test
@@ -40,3 +40,6 @@
 
 RUN: not LLVMFuzzer-SimpleDictionaryTest -dict=%S/dict1.txt -seed=1 -runs=1000000  2>&1 | FileCheck %s
 RUN:     LLVMFuzzer-SimpleDictionaryTest                    -seed=1 -runs=1000000  2>&1 | FileCheck %s --check-prefix=Done1000000
+
+RUN: not LLVMFuzzer-SimpleHashTest -use_traces=1 -seed=1 -runs=100000  2>&1 | FileCheck %s
+RUN:     LLVMFuzzer-SimpleHashTest               -seed=1 -runs=1000000 2>&1 | FileCheck %s --check-prefix=Done1000000