Golangci lint fixes (#195)

* Add golangci-lin as make target
* Fix: could omit type ... from declaration; it will be inferred from the right-hand side (staticcheck)
* Fix func intArrayContains is unused (unused)
* Fix: could use strings.ReplaceAll instead (staticcheck)
* Fix: could expand call to math.Pow (staticcheck)
* Fix: could use tagged switch on `...` (staticcheck)
* Fix: Error return value of `...` is not checked (errcheck)
* Fix: ineffectual assignment to err (ineffassign)
* Fix: There is no need to wait for command completion
* Add cpustat, diskstat and schedstat config
* Use slices to exclude metrics
* Replaced stringArrayContains by slices.Contains
* Replace m[k]=v loop with maps.Copy
* Use module slices from the standard library. Remove use of golang.org/x/exp/slices
* Use SplitSeq and max to modernize code

Makefile

@@ -72,6 +72,11 @@ staticcheck:
 	$(GOBIN) install honnef.co/go/tools/cmd/staticcheck@latest
 	$$($(GOBIN) env GOPATH)/bin/staticcheck ./...
 
+.PHONY: golangci-lint
+golangci-lint:
+	$(GOBIN) install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@latest
+	$$($(GOBIN) env GOPATH)/bin/golangci-lint run
+
 .ONESHELL:
 .PHONY: RPM
 RPM: scripts/cc-metric-collector.spec