VM: Fix Windows 64-bit build on Visual Studio 2012

The UNW_FLAG_EHANDLER #define is now visible in VS2012, causing
a conflict with the definition in os-windows-x86.64.cpp. Added
a #ifndef to only include the definition if it hasn't already
been defined.

diff --git a/vm/os-windows-x86.64.cpp b/vm/os-windows-x86.64.cpp
index c0220851e2364728656d85b4f583c5a6ae7dce73..42e1416ca7ca3413e4cec49c7e08b093e2219fa4 100644 (file)
--- a/vm/os-windows-x86.64.cpp
+++ b/vm/os-windows-x86.64.cpp
@@ -4,7 +4,9 @@ namespace factor {
 
 typedef unsigned char UBYTE;
 
+#ifndef UNW_FLAG_EHANDLER
 const UBYTE UNW_FLAG_EHANDLER = 0x1;
+#endif
 
 struct UNWIND_INFO {
   UBYTE Version : 3;