[Build] Use CMAKE_BINARY_DIR for output paths and version.h include

version.h is now found via CMAKE_BINARY_DIR on the include path instead
of a hardcoded "build/version.h" path. This allows out-of-tree and
multi-config builds to each generate and find their own version header
without colliding.

src/xenia/base/main_win.cc

@@ -15,8 +15,7 @@
 #include "xenia/base/platform_win.h"
 #include "xenia/base/string.h"
 
-// Autogenerated by `xb premake`.
-#include "build/version.h"
+#include "version.h"
 
 // For RequestWin32MMCSS.
 #include <dwmapi.h>