core/std: Remove uses of ++ mode

from stackwalk::frame_address and net_tcp::on_tcp_read_cb
As per #4425

src/libcore/stackwalk.rs

@@ -80,7 +80,7 @@ fn breakpoint() {
     }
 }
 
-fn frame_address(f: &fn(++x: *u8)) {
+fn frame_address(f: &fn(x: *u8)) {
     unsafe {
         rusti::frame_address(f)
     }
@@ -95,7 +95,7 @@ pub mod rustrt {
 pub mod rusti {
     #[abi = "rust-intrinsic"]
     pub extern {
-        pub fn frame_address(f: &once fn(++x: *u8));
+        pub fn frame_address(f: &once fn(x: *u8));
     }
 }
 

src/libstd/net_tcp.rs

@@ -1281,7 +1281,7 @@ impl ToTcpErr for uv::ll::uv_err_data {
 
 extern fn on_tcp_read_cb(stream: *uv::ll::uv_stream_t,
                     nread: libc::ssize_t,
-                    ++buf: uv::ll::uv_buf_t) {
+                    buf: uv::ll::uv_buf_t) {
     unsafe {
         debug!("entering on_tcp_read_cb stream: %? nread: %?",
                         stream, nread);