Fixup various places that were doing &T+'a and do &(T+'a)

src/libstd/io/mod.rs

@@ -911,7 +911,7 @@ impl<'a> Reader for Box<Reader+'a> {
     }
 }
 
-impl<'a> Reader for &'a mut Reader+'a {
+impl<'a> Reader for &'a mut (Reader+'a) {
     fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> { (*self).read(buf) }
 }
 
@@ -1279,7 +1279,7 @@ impl<'a> Writer for Box<Writer+'a> {
     }
 }
 
-impl<'a> Writer for &'a mut Writer+'a {
+impl<'a> Writer for &'a mut (Writer+'a) {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> IoResult<()> { (**self).write(buf) }