Fix bug with * patterns in trans_alt

    enter_opt was handling the (*) case wrong and causing a bounds check
    failure. Fixed it (the test case is one of the extracted ones from
    the reference manual)

src/rustc/middle/trans/alt.rs

@@ -164,7 +164,8 @@ fn enter_opt(tcx: ty::ctxt, m: match, opt: opt, col: uint,
         alt p.node {
           ast::pat_enum(_, subpats) {
             if opt_eq(tcx, variant_opt(tcx, p.id), opt) {
-              some(option::get_or_default(subpats, [])) }
+              some(option::get_or_default(subpats,
+                     vec::from_elem(variant_size, dummy))) }
             else { none }
           }
           ast::pat_ident(_, none) if pat_is_variant(tcx.def_map, p) {