[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/app/emulator_window.cc

@@ -39,8 +39,7 @@
 #include "xenia/ui/ui_event.h"
 #include "xenia/ui/virtual_key.h"
 
-// Autogenerated by `xb premake`.
-#include "build/version.h"
+#include "version.h"
 
 DECLARE_bool(debug);