run-make-support: preserve tooks.mk behavior for EXTRACXXFLAGS

Author: jieyouxu

Diff for: src/tools/run-make-support/src/cc.rs

@@ -162,7 +162,8 @@ pub fn extra_cxx_flags() -> Vec<&'static str> {
         if is_msvc() { vec![] } else { vec!["-lstdc++"] }
     } else {
         match uname() {
-            n if n.contains("Darwin") => vec!["-lc++"],
+            "Darwin" => vec!["-lc++"],
+            "FreeBSD" | "SunOS" | "OpenBSD" => vec![],
             _ => vec!["-lstdc++"],
         }
     }