Make the new microbenchmarks deterministic and rename

Author: eregon

bench/micro/dispatch/dispatch-mono-splat-unsplat.rb renamed to bench/micro/dispatch/dispatch-mono-splat-rest.rb

@@ -4,12 +4,10 @@ def call(*args)
   end
 end
 
-r = Random.new
-
 callees = Array.new(1000) { Callee.new }
-args = Array.new(1000) { Array.new(r.rand(4)) { 1 } }
+args = Array.new(1000) { |i| Array.new(i % 4, 1) }
 
-benchmark 'dispatch-mono-splat' do
+benchmark 'dispatch-mono-splat-rest' do
   i = 0
   while i < 1000
     callees[i].call(*args[i])

bench/micro/dispatch/dispatch-mono-splat.rb

@@ -1,13 +1,11 @@
 class Callee
-  def call(arg1 = nil, arg2 = nil, arg3 = nil, arg4=nil)
+  def call(arg1 = nil, arg2 = nil, arg3 = nil, arg4 = nil)
     :foo
   end
 end
 
-r = Random.new
-
 callees = Array.new(1000) { Callee.new }
-args = Array.new(1000) { Array.new(r.rand(4)) { 1 } }
+args = Array.new(1000) { |i| Array.new(i % 4, 1) }
 
 benchmark 'dispatch-mono-splat' do
   i = 0