metrics: pull library and introduce ResettingTimer and InfluxDB reporter (#15910)

* go-metrics: fork library and introduce ResettingTimer and InfluxDB reporter.

* vendor: change nonsense/go-metrics to ethersphere/go-metrics

* go-metrics: add tests. move ResettingTimer logic from reporter to type.

* all, metrics: pull in metrics package in go-ethereum

* metrics/test: make sure metrics are enabled for tests

* metrics: apply gosimple rules

* metrics/exp, internal/debug: init expvar endpoint when starting pprof server

* internal/debug: tiny comment formatting fix

1 files changed, 7 insertions, 0 deletions

diff --git a/metrics/runtime_no_cgo.go b/metrics/runtime_no_cgo.go
new file mode 100644
index 000000000..616a3b475
--- /dev/null
+++ b/metrics/runtime_no_cgo.go
@@ -0,0 +1,7 @@
+// +build !cgo appengine
+
+package metrics
+
+func numCgoCall() int64 {
+	return 0
+}