Fix includes for unices that don't have chdir declared transitively.

llvm-svn: 156302
diff --git a/clang/lib/Tooling/Tooling.cpp b/clang/lib/Tooling/Tooling.cpp
index 9eb186b..9b4d4e2 100644
--- a/clang/lib/Tooling/Tooling.cpp
+++ b/clang/lib/Tooling/Tooling.cpp
@@ -26,9 +26,11 @@
 #include "llvm/Support/Host.h"
 #include "llvm/Support/raw_ostream.h"
 
-#ifdef _WIN32
 // For chdir, see the comment in ClangTool::run for more information.
+#ifdef _WIN32
 #  include <direct.h>
+#else
+#  include <unistd.h>
 #endif
 
 namespace clang {