kill_proc was removed in kernel 2.6.27; unfortunately we can't fix this
properly, only nvidia can. Looking at nvidia-current, os_kill_process was
removed, so may be it wasn't used by nvidia binary blob (or not really
needed). For now just hack and always return error in os_kill_process,
I made some tests and seems to work (eg. no important things using/needing
os_kill_process).

--- nv/os-interface.c.orig	2008-08-28 13:11:52.000000000 -0300
+++ nv/os-interface.c	2008-08-28 13:12:33.000000000 -0300
@@ -632,7 +632,7 @@ RM_STATUS NV_API_CALL os_kill_process(
     U032 sig
 )
 {
-    return kill_proc(pid, sig, 1) ? RM_ERR_OPERATING_SYSTEM : RM_OK;
+    return /*kill_proc(pid, sig, 1) ?*/ RM_ERR_OPERATING_SYSTEM /*: RM_OK*/;
 }
 
 /*******************************************************************************/