[fuzzer] minor cleanup based on reviews: remove redundant includes, fix a copy-pasto in tests

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227468 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Fuzzer/FuzzerLoop.cpp

@@ -12,9 +12,7 @@
 #include "FuzzerInternal.h"
 #include <sanitizer/asan_interface.h>
 #include <algorithm>
-#include <string>
 #include <iostream>
-#include <stdlib.h>
 
 // This function should be defined by the user.
 extern "C" void TestOneInput(const uint8_t *Data, size_t Size);