Fix Windows build.

* ssize_t isn't defined by default on Windows.
* New public API files need to be defined in a different file for
  Windows.

llvm-svn: 217624
diff --git a/lldb/tools/driver/Driver.cpp b/lldb/tools/driver/Driver.cpp
index 4ed696e..188578e 100644
--- a/lldb/tools/driver/Driver.cpp
+++ b/lldb/tools/driver/Driver.cpp
@@ -39,6 +39,8 @@
 #include "lldb/API/SBThread.h"
 #include "lldb/API/SBProcess.h"
 
+#include "llvm/Support/DataTypes.h"
+
 using namespace lldb;
 
 static void reset_stdin_termios ();