Add missing needs-sanitizer-dataflow directive

Author: jieyouxu

src/tools/compiletest/src/header.rs

@@ -810,6 +810,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "needs-rust-lldb",
     "needs-sanitizer-address",
     "needs-sanitizer-cfi",
+    "needs-sanitizer-dataflow",
     "needs-sanitizer-hwaddress",
     "needs-sanitizer-leak",
     "needs-sanitizer-memory",