- Fixed comments in various system call handlers. Work in progress on new

sys_privctl() call to dynamically start servers and drivers.

- Shutdown sequence slightly adjusted: called as watchdog timer to let the
  busy sys_abort() call from the PM return first.

- Changed umap_bios() to have more restrictive check: BIOS memory is now
  allowed in BIOS_MEM_BEGIN to END (interrupt vectors) and BASE_MEM_TOP
  to UPPER_MEM_END. Hopefully this keeps QEMU and Bochs happy.

kernel/system.h

@@ -82,9 +82,9 @@ _PROTOTYPE( int do_getinfo, (message *m_ptr) );
 #define do_getinfo do_unused
 #endif
 
-_PROTOTYPE( int do_svrctl, (message *m_ptr) );	
-#if ! USE_SVRCTL
-#define do_svrctl do_unused
+_PROTOTYPE( int do_privctl, (message *m_ptr) );	
+#if ! USE_PRIVCTL
+#define do_privctl do_unused
 #endif
 
 _PROTOTYPE( int do_segctl, (message *m_ptr) );