std: Clean out deprecated APIs

Removes all unstable and deprecated APIs prior to the 1.8 release. All APIs that
are deprecated in the 1.8 release are sticking around for the rest of this
cycle.

Some notable changes are:

* The `dynamic_lib` module was moved into `rustc_back` as the compiler still
  relies on a few bits and pieces.
* The `DebugTuple` formatter now special-cases an empty struct name with only
  one field to append a trailing comma.

src/compiletest/compiletest.rs

@@ -11,7 +11,6 @@
 #![crate_type = "bin"]
 
 #![feature(box_syntax)]
-#![feature(dynamic_lib)]
 #![feature(libc)]
 #![feature(rustc_private)]
 #![feature(str_char)]

src/compiletest/procsrv.rs

@@ -8,25 +8,31 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![allow(deprecated)]
-
-use std::dynamic_lib::DynamicLibrary;
+use std::env;
+use std::ffi::OsString;
 use std::io::prelude::*;
 use std::path::PathBuf;
 use std::process::{ExitStatus, Command, Child, Output, Stdio};
 
 fn add_target_env(cmd: &mut Command, lib_path: &str, aux_path: Option<&str>) {
     // Need to be sure to put both the lib_path and the aux path in the dylib
     // search path for the child.
-    let mut path = DynamicLibrary::search_path();
+    let var = if cfg!(windows) {
+        "PATH"
+    } else if cfg!(target_os = "macos") {
+        "DYLD_LIBRARY_PATH"
+    } else {
+        "LD_LIBRARY_PATH"
+    };
+    let mut path = env::split_paths(&env::var_os(var).unwrap_or(OsString::new()))
+                       .collect::<Vec<_>>();
     if let Some(p) = aux_path {
         path.insert(0, PathBuf::from(p))
     }
     path.insert(0, PathBuf::from(lib_path));
 
     // Add the new dylib search path var
-    let var = DynamicLibrary::envvar();
-    let newpath = DynamicLibrary::create_path(&path);
+    let newpath = env::join_paths(&path).unwrap();
     cmd.env(var, newpath);
 }