Get io.mmap working on Windows CE

extra/io/windows/mmap/mmap.factor

@@ -1,7 +1,7 @@
 USING: alien alien.c-types alien.syntax arrays continuations
 destructors generic io.mmap io.nonblocking io.windows
 kernel libc math namespaces quotations sequences windows
-windows.advapi32 windows.kernel32 ;
+windows.advapi32 windows.kernel32 io.backend ;
 IN: io.windows.mmap
 
 TYPEDEF: TOKEN_PRIVILEGES* PTOKEN_PRIVILEGES
@@ -51,12 +51,16 @@ TYPEDEF: TOKEN_PRIVILEGES* PTOKEN_PRIVILEGES
         dup length f f AdjustTokenPrivileges win32-error=0/f
     ] with-process-token ;
 
-: with-privileges ( seq quot -- )
+HOOK: with-privileges io-backend ( seq quot -- ) inline
+
+M: windows-nt-io with-privileges
     over [ [ t set-privilege ] each ] curry compose
     swap [ [ f set-privilege ] each ] curry [ ] cleanup ;
 
-: mmap-open ( path access-mode create-mode flProtect access length -- handle handle address )
-    drop
+M: windows-ce-io with-privileges
+    nip call ;
+
+: mmap-open ( path access-mode create-mode flProtect access -- handle handle address )
     { "SeCreateGlobalPrivilege" "SeLockMemoryPrivilege" } [
         >r >r open-file dup f r> 0 0 f
         CreateFileMapping [ win32-error=0/f ] keep
@@ -68,20 +72,17 @@ TYPEDEF: TOKEN_PRIVILEGES* PTOKEN_PRIVILEGES
     
 M: windows-io <mapped-file> ( path length -- mmap )
     [
-        [
-            >r
+        swap
         GENERIC_WRITE GENERIC_READ bitor
         OPEN_ALWAYS
         PAGE_READWRITE SEC_COMMIT bitor
-            FILE_MAP_ALL_ACCESS r> mmap-open
-        ] keep
-    -roll -rot 2array \ mapped-file construct-boa
+        FILE_MAP_ALL_ACCESS mmap-open
+        -rot 2array
+        \ mapped-file construct-boa
     ] with-destructors ;
 
 M: windows-io close-mapped-file ( mapped-file -- )
     [
-        dup mapped-file-handle [
-            close-always
-        ] each
+        dup mapped-file-handle [ close-always ] each
         mapped-file-address UnmapViewOfFile win32-error=0/f
     ] with-destructors ;