Fix case-sensitive extension check

Author: Javier-varez

tests/compile-test.rs

@@ -44,7 +44,9 @@ fn third_party_crates() -> String {
         };
         if let Some(name) = path.file_name().and_then(OsStr::to_str) {
             for dep in CRATES {
-                if name.starts_with(&format!("lib{}-", dep)) && name.ends_with(".rlib") {
+                if name.starts_with(&format!("lib{}-", dep))
+                    && name.rsplit('.').next().map(|ext| ext.eq_ignore_ascii_case("rlib")) == Some(true)
+                {
                     if let Some(old) = crates.insert(dep, path.clone()) {
                         panic!("Found multiple rlibs for crate `{}`: `{:?}` and `{:?}", dep, old, path);
                     }