* lib/*.rb: Remove unused variable warnings.

Patch by Run Paint [ruby-core:30991]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@29726 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/irb/ext/multi-irb.rb

@@ -29,12 +29,12 @@ module IRB
     end
 
     def thread(key)
-      th, irb = search(key)
+      th, = search(key)
       th
     end
 
     def irb(key)
-      th, irb = search(key)
+      _, irb = search(key)
       irb
     end
 
@@ -62,7 +62,7 @@ module IRB
 
     def kill(*keys)
       for key in keys
-	th, irb = search(key)
+	th, _ = search(key)
 	IRB.fail IrbAlreadyDead unless th.alive?
 	th.exit
       end