make vec fns/methods take imm slices.

this also repairs the unsoundness in typing of unpack_slice,
which was silently converting a const ptr to an imm one.

src/rustc/middle/resolve.rs

@@ -1512,7 +1512,8 @@ fn lookup_in_globs(e: env, globs: [glob_imp_def], sp: span, id: ident,
           none { none }
         }
     }
-    let matches = vec::filter_map(copy globs,
+    let g = copy globs; // FIXME #2405
+    let matches = vec::filter_map(g,
                                   {|x| lookup_in_mod_(e, x, sp, id, ns, dr)});
     if vec::len(matches) == 0u {
         ret none;

src/rustc/middle/trans/native.rs

@@ -120,7 +120,7 @@ fn classify_ty(ty: TypeRef) -> [x86_64_reg_class] {
     }
 
     fn all_mem(cls: [mut x86_64_reg_class]) {
-        vec::iteri(cls) {|i, _c|
+        for uint::range(0u, cls.len()) { |i|
             cls[i] = memory_class;
         }
     }