[ruby/cgi] Use license files same as ruby/ruby

ruby/cgi@defbdf9a30

Author: hsbt

lib/cgi/cgi.gemspec

@@ -25,7 +25,8 @@ Gem::Specification.new do |spec|
   spec.executables   = []
 
   spec.files = [
-    "LICENSE.txt",
+    "COPYING",
+    "BSDL",
     "README.md",
     *Dir["lib{.rb,/**/*.rb}", "bin/*"]  ]