Removed libffi patchs for old Ruby (#143)

Pick
ruby/ruby@92865d8
from `ruby/ruby` repo.

---------

Co-authored-by: Nobuyoshi Nakada <[email protected]>

Author: hsbt

ext/fiddle/win32/fficonfig.h

@@ -34,10 +34,6 @@ Gem::Specification.new do |spec|
     "ext/fiddle/memory_view.c",
     "ext/fiddle/pinned.c",
     "ext/fiddle/pointer.c",
-    "ext/fiddle/win32/fficonfig.h",
-    "ext/fiddle/win32/libffi-3.2.1-mswin.patch",
-    "ext/fiddle/win32/libffi-config.rb",
-    "ext/fiddle/win32/libffi.mk.tmpl",
     "fiddle.gemspec",
     "lib/fiddle.rb",
     "lib/fiddle/closure.rb",