Zig 0.15 fixes / update

[danodonovan]

Fixes so that DOOM-fire can run with zig 0.15

• Zig 0.15 build updates: use root_module + link_libc
• use std.fs.File, stdout.handle, std.Thread.sleep -- compatible with 0.15 API. remove fmtIntSizeBin and print raw bytes
• defensive buffer safety (fixes a segfault I was getting)
• Ctrl+C handling: restores the TTY on exist (WIndows untouched)