dev-ruby/syntax: remove unused patch(es).

Closes: https://bugs.gentoo.org/664042
Closes: https://github.com/gentoo/gentoo/pull/9397

dev-ruby/syntax/files/syntax-1.2.0-require-set.patch

@@ -1,16 +0,0 @@
-commit 22430510b9662edd64e3792c560629daf8aebc82
-Author: Jan Berkel <jan@soundcloud.com>
-Date:   Tue Apr 1 07:00:17 2014 -0400
-
-    Explicitly require 'set'.
-
-diff --git a/lib/syntax/lang/ruby.rb b/lib/syntax/lang/ruby.rb
-index edccda0..90eca56 100644
---- a/lib/syntax/lang/ruby.rb
-+++ b/lib/syntax/lang/ruby.rb
-@@ -1,4 +1,5 @@
- require 'syntax'
-+require 'set'
- 
- module Syntax
-