libcore: Add sys::set_min_stack

Adding this back to the library as a stopgap measure to recover some benchmark
performance. See #1527.

src/libcore/sys.rs

@@ -21,6 +21,7 @@ native mod rustrt {
     fn unsupervise();
     fn shape_log_str<T>(t: *sys::type_desc, data: T) -> str;
     fn rust_set_exit_status(code: int);
+    fn set_min_stack(size: uint);
 }
 
 #[abi = "rust-intrinsic"]
@@ -105,6 +106,22 @@ fn set_exit_status(code: int) {
     rustrt::rust_set_exit_status(code);
 }
 
+// FIXME: #1495 - This shouldn't exist
+#[doc(
+    brief =
+    "Globally set the minimum size, in bytes, of a stack segment",
+    desc =
+    "Rust tasks have segmented stacks that are connected in a linked list \
+     allowing them to start very small and grow very large. In some \
+     situations this can result in poor performance. Calling this function \
+     will set the minimum size of all stack segments allocated in the \
+     future, for all tasks."
+)]
+#[deprecated]
+fn set_min_stack(size: uint) {
+    rustrt::set_min_stack(size);
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;