Migrate fuzzer to use shiny new metrics2 package

go/metrics2/counter.go

 package metrics2
 
 import "sync"
 
 const (
         MEASUREMENT_COUNTER = "counter"
 )
 
 // Counter is a struct used for tracking metrics which increment or decrement.
 type Counter struct {
@@ skipping 33 matching lines @@
         defer c.mtx.Unlock()
         c.m.Update(c.m.Get() - i)
 }
 
 // Reset sets the counter to zero.
 func (c *Counter) Reset() {
         c.mtx.Lock()
         defer c.mtx.Unlock()
         c.m.Update(0)
 }
+
+// Get returns the current value in the counter.
+func (c *Counter) Get() int64 {
+        c.mtx.Lock()
+        defer c.mtx.Unlock()
+        return c.m.Get()
+}