sudo: change password prompt

The current sudo password prompt is "Password: ", while distros like
e.g. Ubuntu and Arch Linux use "[sudo] password for %p: ", where "%p"
expands to the username of the user running sudo.

Adopt the prompt from other distros because it makes it less confusing
when running commands with sudo that themselves ask for a password.

pkgs/tools/security/sudo/default.nix

@@ -22,6 +22,10 @@ stdenv.mkDerivation rec {
     "--with-sendmail=${sendmailPath}"
   ];
 
+  configureFlagsArray = [
+    "--with-passprompt=[sudo] password for %p: "  # intentional trailing space
+  ];
+
   postConfigure =
     ''
     cat >> pathnames.h <<'EOF'