Remove rt::default_sched_threads and RUST_THREADS.

As @alexcrichton says, this was really a libgreen thing, and isn't
relevant now.

As this removes a technically-public function, this is a

[breaking-change]

Conflicts:
	src/libtest/lib.rs

src/libstd/rt/mod.rs

@@ -30,7 +30,7 @@ use thunk::Thunk;
 use usize;
 
 // Reexport some of our utilities which are expected by other crates.
-pub use self::util::{default_sched_threads, min_stack, running_on_valgrind};
+pub use self::util::{min_stack, running_on_valgrind};
 pub use self::unwind::{begin_unwind, begin_unwind_fmt};
 
 // Reexport some functionality from liballoc.

src/libstd/rt/util.rs

@@ -58,29 +58,6 @@ pub fn min_stack() -> uint {
     return amt;
 }
 
-/// Get's the number of scheduler threads requested by the environment
-/// either `RUST_THREADS` or `num_cpus`.
-#[allow(deprecated)]
-pub fn default_sched_threads() -> uint {
-    use os;
-    match env::var("RUST_THREADS") {
-        Ok(nstr) => {
-            let opt_n: Option<uint> = nstr.parse().ok();
-            match opt_n {
-                Some(n) if n > 0 => n,
-                _ => panic!("`RUST_THREADS` is `{}`, should be a positive integer", nstr)
-            }
-        }
-        Err(..) => {
-            if limit_thread_creation_due_to_osx_and_valgrind() {
-                1
-            } else {
-                os::num_cpus()
-            }
-        }
-    }
-}
-
 // Indicates whether we should perform expensive sanity checks, including rtassert!
 //
 // FIXME: Once the runtime matures remove the `true` below to turn off rtassert,

src/libtest/lib.rs

@@ -44,6 +44,7 @@
 #![feature(std_misc)]
 #![feature(libc)]
 #![feature(set_stdio)]
+#![feature(os)]
 
 extern crate getopts;
 extern crate serialize;
@@ -841,8 +842,8 @@ fn run_tests<F>(opts: &TestOpts,
     Ok(())
 }
 
+#[allow(deprecated)]
 fn get_concurrency() -> uint {
-    use std::rt;
     match env::var("RUST_TEST_THREADS") {
         Ok(s) => {
             let opt_n: Option<uint> = s.parse().ok();
@@ -852,7 +853,11 @@ fn get_concurrency() -> uint {
             }
         }
         Err(..) => {
-            rt::default_sched_threads()
+            if std::rt::util::limit_thread_creation_due_to_osx_and_valgrind() {
+                1
+            } else {
+                std::os::num_cpus()
+            }
         }
     }
 }