Add vendor files for go build

vendor/github.com/alecthomas/chroma/lexers/b/bnf.go

@@ -0,0 +1,24 @@
+package b
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+	"github.com/alecthomas/chroma/lexers/internal"
+)
+
+// Bnf lexer.
+var Bnf = internal.Register(MustNewLexer(
+	&Config{
+		Name:      "BNF",
+		Aliases:   []string{"bnf"},
+		Filenames: []string{"*.bnf"},
+		MimeTypes: []string{"text/x-bnf"},
+	},
+	Rules{
+		"root": {
+			{`(<)([ -;=?-~]+)(>)`, ByGroups(Punctuation, NameClass, Punctuation), nil},
+			{`::=`, Operator, nil},
+			{`[^<>:]+`, Text, nil},
+			{`.`, Text, nil},
+		},
+	},
+))