[libFuzzer] Avoid STL in MSan test.

[morehouse]

Summary

STL can cause MSan false positives if lib[std]c++ isn't instrumented with MSan

[kcc]

err... partially taking my word back.. I do want to keep this test to use STL.
Instead of this change, please create another test, e.g. SimpleTestStdio.cpp, that won't use STL, and use the new test in msan runs.

[morehouse]

• Revert "[libFuzzer] Avoid std::cout in SimpleTest."
• Create SimpleTestStdio.cpp without STL.

[kcc]

LGTM

compiler-rt/test/fuzzer/SimpleTestStdio.cpp

+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+
+// Simple test for a fuzzer. The fuzzer must find the string "Hi!".
+#include <assert.h>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+
+static volatile int Sink;
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  assert(Data);
+  if (Size > 0 && Data[0] == 'H') {
+    Sink = 1;
+    if (Size > 1 && Data[1] == 'i') {
+      Sink = 2;
+      if (Size > 2 && Data[2] == '!') {
+        fprintf(stderr, "BINGO; Found the target, exiting\n");
+        exit(0);
+      }
+    }
+  }
+  return 0;
+}
+

compiler-rt/test/fuzzer/msan.test

 REQUIRES: msan
-RUN: %msan_compiler %S/SimpleTest.cpp -o %t
+RUN: %msan_compiler %S/SimpleTestStdio.cpp -o %t
 RUN: not %run %t -seed=1 -runs=10000000 2>&1 | FileCheck %s --check-prefix=NO-REPORT
 
 RUN: %msan_compiler %S/SimpleCmpTest.cpp -o %t
 RUN: not %run %t -seed=1 -runs=10000000 2>&1 | FileCheck %s --check-prefix=NO-REPORT
 
 RUN: %msan_compiler %S/MemcmpTest.cpp -o %t
 RUN: not %run %t -seed=1 -runs=10000000 2>&1 | FileCheck %s --check-prefix=NO-REPORT