Use linux? word now

core/cpu/ppc/architecture/architecture.factor

@@ -295,7 +295,7 @@ M: ppc-backend %cleanup ( alien-node -- ) drop ;
 M: ppc-backend value-structs?
     #! On Linux/PPC, value structs are passed in the same way
     #! as reference structs, we just have to make a copy first.
-    os "linux" = not ;
+    linux? not ;
 
 M: ppc-backend fp-shadows-int? ( -- ? ) macosx? ;
 

core/cpu/ppc/ppc.factor

@@ -6,7 +6,7 @@ namespaces alien.c-types kernel system combinators ;
         4 "longlong" c-type set-c-type-align
         4 "ulonglong" c-type set-c-type-align
     ] }
-    { [ os "linux" = ] [
+    { [ linux? ] [
         t "longlong" c-type set-c-type-stack-align?
         t "ulonglong" c-type set-c-type-stack-align?
     ] }