Add the 'avr-std-stub' crate to provide panic handler and exception handler personality fn

Author: dylanmckay

Cargo.lock

@@ -7,3 +7,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+avr-std-stub = "1.0"

Cargo.toml

@@ -1,3 +1,8 @@
+#![no_std]
+#![no_main]
+
+extern crate avr_std_stub;
+
+#[no_mangle]
 fn main() {
-    println!("Hello, world!");
 }