deactivate apic timer when globally disabled

bochs/cpu/apic.cc

@@ -303,6 +303,11 @@ void bx_local_apic_c::set_base(bx_phy_address newbase)
     for(int i=0; i<APIC_LVT_ENTRIES; i++) {
       lvt[i] = 0x10000;	// all LVT are masked
     }
+
+    if(timer_active) {
+      bx_pc_system.deactivate_timer(timer_handle);
+      timer_active = 0;
+    }
   }
 }