www/deno: fix three patch correctness bugs found in review

• patch-cli_standalone_binary.rs: restore Linux ELF target support by using || instead of replacing the linux check with freebsd
• patch-ext_os_lib.rs: fix FreeBSD rss() return type usize -> u64 to match all other platforms; use %%PREFIX%% placeholder so post-patch REINPLACE_CMD correctly substitutes the install prefix at build time
• Makefile: add s|%%PREFIX%%|${PREFIX}| substitution for ext/os/lib.rs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>