Add tests for no-stack-check attr and codegen option

src/test/run-make/no-stack-check/Makefile

+-include ../tools.mk
+
+all:
+	$(RUSTC) -O --emit asm attr.rs
+	! grep -q morestack $(TMPDIR)/attr.s
+	$(RUSTC) -O --emit asm flag.rs
+	grep -q morestack $(TMPDIR)/flag.s
+	$(RUSTC) -O --emit asm -C no-stack-check flag.rs
+	! grep -q morestack $(TMPDIR)/flag.s

src/test/run-make/no-stack-check/attr.rs

+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![crate_type="lib"]
+
+extern {
+    // Prevents optimizing away the stack buffer.
+    // This symbol is undefined, but the code doesn't need to pass
+    // the linker.
+    fn black_box(ptr: *const u8);
+}
+
+#[no_stack_check]
+pub unsafe fn foo() {
+    // Make sure we use the stack
+    let x: [u8, ..50] = [0, ..50];
+    black_box(x.as_ptr());
+}

src/test/run-make/no-stack-check/flag.rs

+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![crate_type="lib"]
+
+extern {
+    // Prevents optimizing away the stack buffer.
+    // This symbol is undefined, but the code doesn't need to pass
+    // the linker.
+    fn black_box(ptr: *const u8);
+}
+
+pub unsafe fn foo() {
+    // Make sure we use the stack
+    let x: [u8, ..50] = [0, ..50];
+    black_box(x.as_ptr());
+}