Update wiki URLs to point directly to pages in warning messages

[olleolleolle]

While investigating an issue, socketry/falcon#64, elsewhere, I found that in warnings emitted by JRuby, the direct link to a specific wiki page link had become out of date, and didn't point to the exact page anymore. It just pointed to the start page.

With this change, it does again point to the exact pages.

TODO

Here are other files that need a change, please make that change, if you find that before I do. Have a nice day!

• jruby/core/src/main/java/org/jruby/java/proxies/JavaProxy.java

  Line 575 in a309a88

  private static final String NONPERSISTENT_IVAR_MESSAGE = "instance vars on non-persistent Java type {0} (http://wiki.jruby.org/Persistence)";

• jruby/core/src/main/java/org/jruby/ext/jruby/JRubyUtilLibrary.java

  Line 86 in a309a88

  runtime.getWarnings().warn("ObjectSpace impacts performance. See http://wiki.jruby.org/PerformanceTuning#dont-enable-objectspace");

• jruby/core/src/main/java/org/jruby/ext/socket/RubySocket.java

  Line 717 in df79d1f

  private static final String JRUBY_SERVER_SOCKET_ERROR =