cleanup cpu_set_debug_excp_handler

There are no users left for previous exception handler returned from
cpu_set_debug_excp_handler. It should simplify code a little.

Signed-off-by: Igor Mammedov <[email protected]>
diff --git a/cpu-exec.c b/cpu-exec.c
index 624c409..24607fb 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -156,12 +156,9 @@
 
 static CPUDebugExcpHandler *debug_excp_handler;
 
-CPUDebugExcpHandler *cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
+void cpu_set_debug_excp_handler(CPUDebugExcpHandler *handler)
 {
-    CPUDebugExcpHandler *old_handler = debug_excp_handler;
-
     debug_excp_handler = handler;
-    return old_handler;
 }
 
 static void cpu_handle_debug_exception(CPUArchState *env)