Don't check Makefile directives

Author: jieyouxu

src/tools/compiletest/src/header.rs

@@ -964,6 +964,17 @@ fn iter_header(
         {
             let directive_ln = original_directive_line.trim();
 
+            // Let Makefiles just get handled in the regular way.
+            if testfile.extension().is_some_and(|e| e != "rs") {
+                it(HeaderLine {
+                    line_number,
+                    original_line,
+                    header_revision,
+                    directive: original_directive_line,
+                });
+                continue;
+            }
+
             if let Some((directive_name, _)) = directive_ln.split_once([':', ' ']) {
                 if KNOWN_DIRECTIVE_NAMES.contains(&directive_name) {
                     it(HeaderLine {