fix(lint): correct stale benchmark comment about the ColumnOfOffset fix

The comment described an earlier bytes.LastIndexByte approach that was
abandoned (benchmarking showed no SIMD assembly backs LastIndexByte on
any platform) in favor of the binary-search fix actually shipped.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UCh2j2oeSw6UgNsmpjRonL

Author: claude

internal/lint/column_bench_test.go

@@ -5,12 +5,11 @@ import (
 	"testing"
 )
 
-// BenchmarkColumnOfOffset_LongLine exercises the worst case for
-// ColumnOfOffset: an offset near the end of a very long line, forcing a
-// full backward scan to find the line start. Per
-// docs/development/high-performance-go.md, a hand-rolled byte-at-a-time
-// scan is not vectorized by the compiler; bytes.LastIndexByte is SIMD
-// assembly on amd64.
+// BenchmarkColumnOfOffset_LongLine exercises the former worst case for
+// ColumnOfOffset: an offset near the end of a very long line, which used
+// to force a full backward byte-at-a-time scan to find the line start.
+// ColumnOfOffset now reuses LineOfOffset's cached newline index via a
+// binary search instead (docs/development/high-performance-go.md).
 func BenchmarkColumnOfOffset_LongLine(b *testing.B) {
 	line := bytes.Repeat([]byte("x"), 8192)
 	src := append(append([]byte("prefix\n"), line...), '\n')