Use prereq instead of p for variable name

https://github.com/ruby/rake/pull/183/files/a094e2584295005c7b1ee1419b7bf9136b9f4411#r94092645

Author: aycabta

lib/rake/file_task.rb

@@ -29,12 +29,12 @@ def timestamp
 
     # Are there any prerequisites with a later time than the given time stamp?
     def out_of_date?(stamp)
-      @prerequisites.any? { |p|
-        ptask = application[p, @scope]
-        if ptask.instance_of?(Rake::FileTask)
-          ptask.timestamp > stamp || ptask.needed?
+      @prerequisites.any? { |prereq|
+        prereq_task = application[prereq, @scope]
+        if prereq_task.instance_of?(Rake::FileTask)
+          prereq_task.timestamp > stamp || prereq_task.needed?
         else
-          ptask.timestamp > stamp
+          prereq_task.timestamp > stamp
         end
       }
     end