[msan] Fix a typo in test.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@177059 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/msan/tests/msan_test.cc b/lib/msan/tests/msan_test.cc
index e2628af..a467e0d 100644
--- a/lib/msan/tests/msan_test.cc
+++ b/lib/msan/tests/msan_test.cc
@@ -670,7 +670,7 @@
   char *x = strndup(buf, 2);
   EXPECT_NOT_POISONED(x[0]);
   EXPECT_POISONED(x[1]);
-  EXPECT_NOT_POISONED(x[3]);
+  EXPECT_NOT_POISONED(x[2]);
   free(x);
 }