Fix compilation on internix


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14588 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/CommandLine.cpp b/lib/Support/CommandLine.cpp
index 3454ffc..2337e2e 100644
--- a/lib/Support/CommandLine.cpp
+++ b/lib/Support/CommandLine.cpp
@@ -23,6 +23,7 @@
 #include <iostream>
 #include <cstdlib>
 #include <cerrno>
+#include <cstring>
 using namespace llvm;
 
 using namespace cl;