basis: some more os require cleanup.

basis/environment/unix/unix.factor

@@ -31,7 +31,4 @@ M: unix set-os-envs-pointer ( malloc -- ) environ set-void* ;
 M: unix (set-os-envs) ( seq -- )
     utf8 strings>alien malloc-byte-array set-os-envs-pointer ;
 
-os {
-    { macosx [ "environment.unix.macosx" require ] }
-    [ drop ]
-} case
+os macosx? [ "environment.unix.macosx" require ] when

basis/unix/utmpx/utmpx.factor

@@ -1,9 +1,8 @@
 ! Copyright (C) 2008 Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: alien.c-types alien.data alien.syntax combinators
+USING: accessors alien.c-types alien.data alien.syntax
 continuations io.encodings.string io.encodings.utf8 kernel
-sequences strings calendar system accessors unix unix.time
-unix.ffi calendar.unix vocabs classes.struct ;
+sequences system unix.ffi vocabs ;
 IN: unix.utmpx
 
 CONSTANT: EMPTY 0
@@ -48,7 +47,4 @@ M: unix new-utmpx-record
         produce nip
     ] with-utmpx ;
 
-os {
-    { macosx [ "unix.utmpx.macosx" require ] }
-    { linux [ "unix.utmpx.linux" require ] }
-} case
+"unix.utmpx." os name>> append require