*: fix all unused warnings

From golangci-lint.

pkg/compiler/codegen.go

@@ -1521,33 +1521,6 @@ func getJumpForToken(tok token.Token, typ types.Type) (opcode.Opcode, bool) {
 	return 0, false
 }
 
-// getByteArray returns byte array value from constant expr.
-// Only literals are supported.
-func (c *codegen) getByteArray(expr ast.Expr) []byte {
-	switch t := expr.(type) {
-	case *ast.CompositeLit:
-		if !isByteSlice(c.typeOf(t.Type)) {
-			return nil
-		}
-		buf := make([]byte, len(t.Elts))
-		for i := 0; i < len(t.Elts); i++ {
-			t := c.typeAndValueOf(t.Elts[i])
-			val, _ := constant.Int64Val(t.Value)
-			buf[i] = byte(val)
-		}
-		return buf
-	case *ast.CallExpr:
-		if tv := c.typeAndValueOf(t.Args[0]); tv.Value != nil {
-			val := constant.StringVal(tv.Value)
-			return []byte(val)
-		}
-
-		return nil
-	default:
-		return nil
-	}
-}
-
 func (c *codegen) convertSyscall(f *funcScope, expr *ast.CallExpr) {
 	for _, arg := range expr.Args[1:] {
 		ast.Walk(c, arg)