For compiling on FreeBSD

llvm-svn: 104616
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 5b00ffede4be6d9a8649ab01d75b8980a941a72e
diff --git a/src/thread.cpp b/src/thread.cpp
index 2a6b205..f2db6d5 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -9,6 +9,7 @@
 
 #include "thread"
 #include "exception"
+#include <sys/types.h>
 #include <sys/sysctl.h>
 
 _LIBCPP_BEGIN_NAMESPACE_STD