Add cross-compiled binaries for Ruby 1.8 and 1.9 to the gem spec.

By default it looks like rake-compiler doesn't modify the gem spec
appropriately when we're cross-compiling for multiple Ruby versions.
Added some lines to remove "lib/fox16.so" from the gem spec's list
of files to include, and then added "lib/1.8/fox16.so" and "lib/1.9/fox16.so"
back to the list, so that we get the correct result.

Rakefile

@@ -55,9 +55,11 @@ Rake::ExtensionTask.new("fox16", hoe.spec) do |ext|
   ext.cross_config_options << "--with-fxscintilla-lib=/home/lyle/mingw/lib"
   
   # perform alterations on the gem spec when cross-compiling
-# ext.cross_compiling do |gem_spec|
-#   gem_spec.post_install_message = "You installed the binary version of this gem!" 
-# end
+  ext.cross_compiling do |gem_spec|
+    gem_spec.files.delete "lib/fox16.so"
+    gem_spec.files << "lib/1.8/fox16.so"
+    gem_spec.files << "lib/1.9/fox16.so"
+  end
 end
 
 # Make the compile task's list of dependencies begin with the :configure task