Obscure various literal uses of the todo marker

In each case, use a circumlocution.

CHANGELOG.md

@@ -2045,7 +2045,7 @@ release 0.1.0 (scheduled March 2022).
 
 - We store fewer needless fields from Tor directory documents. ([!151],
   [!165])
-- We've gone through and converted _every_ `XXXX` comment in our code (which
+- We've gone through and converted _every_ <code>XX&#88;X</code> comment in our code (which
   indicated a must-fix issue) into a ticket, or a `TODO`. ([#231])
 - Our SOCKS code is much more careful about sending error messages if
   an error occurs before the SOCKS connection succeeds. ([!189])

maint/binary_size

@@ -6,7 +6,7 @@
 set -euo pipefail
 
 ORIGDIR=$(pwd)
-TMPDIR=$(mktemp -d -t arti_binsize.XXXXXX)
+TMPDIR=$(mktemp -d -t arti_binsize."XX""XX""XX")
 trap 'cd "$ORIGDIR" && rm -rf "$TMPDIR"' 0
 
 RUST_TARGET=$(rustc -vV | sed -n 's|host: ||p')

maint/fixup-features/src/main.rs

@@ -120,7 +120,7 @@ fn arti_dependencies(dependencies: &Table) -> Vec<Dependency> {
 
 /// A complaint that we add to features which are not reachable according to
 /// rule 3.
-const COMPLAINT: &str = "# XXXX Add this to a top-level feature!\n";
+const COMPLAINT: &str = "# XX\x58X Add this to a top-level feature!\n";
 
 impl Crate {
     /// Try to read a crate's Cargo.toml from a given filename.