tail: arithmetic overflow (overflow-checks) on `-c -N` with N = 2^63 (i64::MIN negate)

tail -c -9223372036854775808 FILE panics with attempt to negate with overflow under overflow-checks.

$ yes | head -c 8192 > f      # a regular file LARGER than the block size (~4 KiB)
$ # debug build (overflow-checks on by default) — clean-rebuild to avoid a stale binary
$ cargo build -q -p uu_tail --bin tail
$ ./target/debug/tail -c -9223372036854775808 f >/dev/null
thread 'main' panicked at src/uu/tail/src/tail.rs:472:17:
attempt to negate with overflow
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
$ echo $?
101

Root cause

In bounded_tail, the Bytes(Negative(count)) arm computes the seek offset as -(*count as i64); for count = 9223372036854775808 (2^63), count as i64 is i64::MIN, and negating i64::MIN overflows i64. A debug (or release + -C overflow-checks) build aborts (exit 101); a normal release build wraps silently and exits 0.

https://github.com/uutils/coreutils/blob/ddc98c2547448e43cb58736048103f4ab6a07f82/src/uu/tail/src/tail.rs#L471-L476

Start in src/uu/tail/src/tail.rs around lines 471-476 and inspect the bounded_tail Bytes(Negative(count)) branch. Reproduce the issue with the cargo build command and the 2^63-byte tail invocation from the report, then verify the debug build no longer panics or exits 101 for that input.