Use Frame*.

stepmania/src/archutils/Unix/Backtrace.h

@@ -3,6 +3,9 @@
 
 /* This API works like backtrace_pointers(), to retrieve a stack trace. */
 
+#if defined(CPU_PPC)
+struct Frame;
+#endif
 /* This contains the information necessary to backtrace a thread. */
 struct BacktraceContext
 {
@@ -15,7 +18,8 @@ struct BacktraceContext
 #endif
 
 #if defined(CPU_PPC)
-	void *FramePtr, *PC;
+	const Frame *FramePtr;
+	const void *PC;
 #endif
 };