[AVR] Update the compiletest library to recognize AVR as a 16-bit target

Author: dylanmckay

src/tools/compiletest/src/util.rs

@@ -115,6 +115,8 @@ pub fn matches_env(triple: &str, name: &str) -> bool {
 pub fn get_pointer_width(triple: &str) -> &'static str {
     if (triple.contains("64") && !triple.ends_with("gnux32")) || triple.starts_with("s390x") {
         "64bit"
+    } else if triple.starts_with("avr") {
+        "16bit"
     } else {
         "32bit"
     }