Revert "Fix for newest breakage, closes #3"

This reverts commit 030c12f3600d2630b96670ad72c04dfb6aa8809e.

riscv-rt/Cargo.toml

@@ -11,7 +11,3 @@ license = "ISC"
 [dependencies]
 r0 = "^0.2.1"
 riscv = { path = "../riscv" }
-
-[build-dependencies]
-rustc_version = "0.2.1"
-chrono = "0.4.0"

riscv-rt/build.rs

@@ -1,20 +1,10 @@
-extern crate chrono;
-extern crate rustc_version;
-
 // NOTE: Adapted from cortex-m/build.rs
 use std::env;
 use std::fs::File;
 use std::io::Write;
 use std::path::PathBuf;
 
-use chrono::NaiveDate;
-
 fn main() {
-    let meta = rustc_version::version_meta().unwrap();
-	// newest nightlies don't need 'extern crate compiler_builtins'
-    if meta.commit_date.unwrap().parse::<NaiveDate>().unwrap() < NaiveDate::from_ymd(2018, 04, 07) {
-        println!("cargo:rustc-cfg=needs_cb")
-    }
     // Put the linker script somewhere the linker can find it
     let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
     File::create(out.join("link.x"))

riscv-rt/src/lib.rs

@@ -160,7 +160,7 @@
 #![deny(missing_docs)]
 #![deny(warnings)]
 #![feature(asm)]
-#![cfg_attr(needs_cb, feature(compiler_builtins_lib))]
+#![feature(compiler_builtins_lib)]
 #![feature(const_fn)]
 #![feature(global_asm)]
 #![feature(lang_items)]
@@ -168,7 +168,6 @@
 #![feature(naked_functions)]
 #![feature(used)]
 
-#[cfg(needs_cb)]
 extern crate compiler_builtins;
 extern crate riscv;
 extern crate r0;