gems: include vendored metrisk without hitime dependency

hitime is only needed for Metriks::Timer and requires native extensions.
Those do not compile with default settings under Ubuntu 26.04 or Alpine 3.24.

lib/metriks/meter.rb

@@ -0,0 +1,88 @@
+# Vendored from metriks 0.9.9.8 — https://github.com/eric/metriks
+# Copyright (c) 2012 Eric Lindvall, MIT licensed.
+# Trimmed to the subset dyndnsd uses (meters + registry + reporters).
+
+
+require 'metriks/ewma'
+
+module Metriks
+  class Meter
+    TICK_INTERVAL = 5.0
+
+    def initialize(averager_klass = Metriks::EWMA)
+      @count = Atomic.new(0)
+      @start_time = Time.now.to_f
+      @last_tick = Atomic.new(@start_time)
+
+      @m1_rate  = averager_klass.new_m1
+      @m5_rate  = averager_klass.new_m5
+      @m15_rate = averager_klass.new_m15
+    end
+
+    def clear
+      @count.value = 0
+      @start_time = Time.now.to_f
+      @last_tick.value = @start_time
+      @m1_rate.clear
+      @m5_rate.clear
+      @m15_rate.clear
+    end
+
+    def tick
+      @m1_rate.tick
+      @m5_rate.tick
+      @m15_rate.tick
+    end
+
+    def tick_if_nessesary
+      old_tick = @last_tick.value
+      new_tick = Time.new.to_f
+      age = new_tick - old_tick
+      if age > TICK_INTERVAL && @last_tick.compare_and_swap(old_tick, new_tick)
+        required_ticks = age / TICK_INTERVAL
+        required_ticks.to_i.times do
+          tick
+        end
+      end
+    end
+
+    def mark(val = 1)
+      tick_if_nessesary
+      @count.update { |v| v + val }
+      @m1_rate.update(val)
+      @m5_rate.update(val)
+      @m15_rate.update(val)
+    end
+
+    def count
+      @count.value
+    end
+
+    def one_minute_rate
+      tick_if_nessesary
+      @m1_rate.rate
+    end
+
+    def five_minute_rate
+      tick_if_nessesary
+      @m5_rate.rate
+    end
+
+    def fifteen_minute_rate
+      tick_if_nessesary
+      @m15_rate.rate
+    end
+
+    def mean_rate
+      if count == 0
+        return 0.0
+      else
+        elapsed = Time.now.to_f - @start_time
+        count / elapsed
+      end
+    end
+
+    def stop
+    end
+  end
+end