[rubygems/rubygems] Add a FreeBSD platform helper

https://github.com/rubygems/rubygems/commit/535c83d5be

lib/rubygems.rb

@@ -1012,6 +1012,13 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     RUBY_PLATFORM.include?("solaris")
   end
 
+  ##
+  # Is this platform FreeBSD
+
+  def self.freebsd_platform?
+    RbConfig::CONFIG["host_os"].to_s.include?("bsd")
+  end
+
   ##
   # Load +plugins+ as Ruby files