compiletest: Fix typo in get_lib_name(); .lib -> .rlib

Author: Enselic

src/tools/compiletest/src/runtest.rs

@@ -86,7 +86,7 @@ fn get_lib_name(lib: &str, dylib: bool) -> String {
     // In some casess (e.g. MUSL), we build a static
     // library, rather than a dynamic library.
     // In this case, the only path we can pass
-    // with '--extern-meta' is the '.lib' file
+    // with '--extern-meta' is the '.rlib' file
     if !dylib {
         return format!("lib{}.rlib", lib);
     }