vendor: update buildkit to master@cbfd4023383d

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/moby/patternmatcher/ignorefile/ignorefile.go

@@ -0,0 +1,73 @@
+package ignorefile
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"path/filepath"
+	"strings"
+)
+
+// ReadAll reads an ignore file from a reader and returns the list of file
+// patterns to ignore, applying the following rules:
+//
+//   - An UTF8 BOM header (if present) is stripped.
+//   - Lines starting with "#" are considered comments and are skipped.
+//
+// For remaining lines:
+//
+//   - Leading and trailing whitespace is removed from each ignore pattern.
+//   - It uses [filepath.Clean] to get the shortest/cleanest path for
+//     ignore patterns.
+//   - Leading forward-slashes ("/") are removed from ignore patterns,
+//     so "/some/path" and "some/path" are considered equivalent.
+func ReadAll(reader io.Reader) ([]string, error) {
+	if reader == nil {
+		return nil, nil
+	}
+
+	var excludes []string
+	currentLine := 0
+	utf8bom := []byte{0xEF, 0xBB, 0xBF}
+
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		scannedBytes := scanner.Bytes()
+		// We trim UTF8 BOM
+		if currentLine == 0 {
+			scannedBytes = bytes.TrimPrefix(scannedBytes, utf8bom)
+		}
+		pattern := string(scannedBytes)
+		currentLine++
+		// Lines starting with # (comments) are ignored before processing
+		if strings.HasPrefix(pattern, "#") {
+			continue
+		}
+		pattern = strings.TrimSpace(pattern)
+		if pattern == "" {
+			continue
+		}
+		// normalize absolute paths to paths relative to the context
+		// (taking care of '!' prefix)
+		invert := pattern[0] == '!'
+		if invert {
+			pattern = strings.TrimSpace(pattern[1:])
+		}
+		if len(pattern) > 0 {
+			pattern = filepath.Clean(pattern)
+			pattern = filepath.ToSlash(pattern)
+			if len(pattern) > 1 && pattern[0] == '/' {
+				pattern = pattern[1:]
+			}
+		}
+		if invert {
+			pattern = "!" + pattern
+		}
+
+		excludes = append(excludes, pattern)
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	return excludes, nil
+}