[ruby/optparse] gemspec: Explicitly list 0 executables

This gem exposes no executable files.

ruby/optparse@d14bf83007

Author: olleolleolle

lib/optparse/optparse.gemspec

@@ -28,6 +28,6 @@ Gem::Specification.new do |spec|
     }
   end
   spec.bindir        = "exe"
-  spec.executables   = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
+  spec.executables   = []
   spec.require_paths = ["lib"]
 end