Defines starting with `s' in kern

• SIGPROP kern/kern_sig.c:36
• snd kern/uipc_usrreq.c:149
• SP kern/sys_process.c:136
• SQSIZE kern/kern_synch.c:242
• STK_PARAMS kern/sys_generic.c:368
• szsigcode kern/kern_exec.c:46