Fix build on Linux.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68269 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Triple.cpp b/lib/Support/Triple.cpp
index 6324ead..5310c3a 100644
--- a/lib/Support/Triple.cpp
+++ b/lib/Support/Triple.cpp
@@ -9,6 +9,7 @@
 
 #include "llvm/ADT/Triple.h"
 #include <cassert>
+#include <cstring>
 using namespace llvm;
 
 //