[srv.init] Serve a service locator protocol from init

The init process now serves as a service locator for its children,
passing all children a mailbox handle on which it is serving the service
locator protocol.

src/libraries/j6/j6.module

@@ -2,8 +2,10 @@
 
 j6 = module("j6",
     kind = "lib",
+    deps = [ "util" ],
     sources = [
         "init.cpp",
+        "protocol_ids.cpp",
         "syscalls.s.cog",
         "sysconf.cpp.cog",
     ],
@@ -12,6 +14,8 @@ j6 = module("j6",
         "j6/errors.h",
         "j6/flags.h",
         "j6/init.h",
+        "j6/protocols.h",
+        "j6/protocols/service_locator.h",
         "j6/syscalls.h.cog",
         "j6/sysconf.h.cog",
         "j6/types.h",