Update common Prometheus files (prometheus#455)

Signed-off-by: prombot <prometheus-team@googlegroups.com>

Makefile.common

@@ -36,29 +36,6 @@ GO_VERSION        ?= $(shell $(GO) version)
 GO_VERSION_NUMBER ?= $(word 3, $(GO_VERSION))
 PRE_GO_111        ?= $(shell echo $(GO_VERSION_NUMBER) | grep -E 'go1\.(10|[0-9])\.')
 
-GOVENDOR :=
-GO111MODULE :=
-ifeq (, $(PRE_GO_111))
-	ifneq (,$(wildcard go.mod))
-		# Enforce Go modules support just in case the directory is inside GOPATH (and for Travis CI).
-		GO111MODULE := on
-
-		ifneq (,$(wildcard vendor))
-			# Always use the local vendor/ directory to satisfy the dependencies.
-			GOOPTS := $(GOOPTS) -mod=vendor
-		endif
-	endif
-else
-	ifneq (,$(wildcard go.mod))
-		ifneq (,$(wildcard vendor))
-$(warning This repository requires Go >= 1.11 because of Go modules)
-$(warning Some recipes may not work as expected as the current Go runtime is '$(GO_VERSION_NUMBER)')
-		endif
-	else
-		# This repository isn't using Go modules (yet).
-		GOVENDOR := $(FIRST_GOPATH)/bin/govendor
-	endif
-endif
 PROMU        := $(FIRST_GOPATH)/bin/promu
 pkgs          = ./...
 
@@ -150,58 +127,47 @@ common-check_license:
 .PHONY: common-deps
 common-deps:
 	@echo ">> getting dependencies"
-ifdef GO111MODULE
-	GO111MODULE=$(GO111MODULE) $(GO) mod download
-else
-	$(GO) get $(GOOPTS) -t ./...
-endif
+	$(GO) mod download
 
 .PHONY: update-go-deps
 update-go-deps:
 	@echo ">> updating Go dependencies"
 	@for m in $$($(GO) list -mod=readonly -m -f '{{ if and (not .Indirect) (not .Main)}}{{.Path}}{{end}}' all); do \
 		$(GO) get -d $$m; \
 	done
-	GO111MODULE=$(GO111MODULE) $(GO) mod tidy
-ifneq (,$(wildcard vendor))
-	GO111MODULE=$(GO111MODULE) $(GO) mod vendor
-endif
+	$(GO) mod tidy
 
 .PHONY: common-test-short
 common-test-short: $(GOTEST_DIR)
 	@echo ">> running short tests"
-	GO111MODULE=$(GO111MODULE) $(GOTEST) -short $(GOOPTS) $(pkgs)
+	$(GOTEST) -short $(GOOPTS) $(pkgs)
 
 .PHONY: common-test
 common-test: $(GOTEST_DIR)
 	@echo ">> running all tests"
-	GO111MODULE=$(GO111MODULE) $(GOTEST) $(test-flags) $(GOOPTS) $(pkgs)
+	$(GOTEST) $(test-flags) $(GOOPTS) $(pkgs)
 
 $(GOTEST_DIR):
 	@mkdir -p $@
 
 .PHONY: common-format
 common-format:
 	@echo ">> formatting code"
-	GO111MODULE=$(GO111MODULE) $(GO) fmt $(pkgs)
+	$(GO) fmt $(pkgs)
 
 .PHONY: common-vet
 common-vet:
 	@echo ">> vetting code"
-	GO111MODULE=$(GO111MODULE) $(GO) vet $(GOOPTS) $(pkgs)
+	$(GO) vet $(GOOPTS) $(pkgs)
 
 .PHONY: common-lint
 common-lint: $(GOLANGCI_LINT)
 ifdef GOLANGCI_LINT
 	@echo ">> running golangci-lint"
-ifdef GO111MODULE
 # 'go list' needs to be executed before staticcheck to prepopulate the modules cache.
 # Otherwise staticcheck might fail randomly for some reason not yet explained.
-	GO111MODULE=$(GO111MODULE) $(GO) list -e -compiled -test=true -export=false -deps=true -find=false -tags= -- ./... > /dev/null
-	GO111MODULE=$(GO111MODULE) $(GOLANGCI_LINT) run $(GOLANGCI_LINT_OPTS) $(pkgs)
-else
-	$(GOLANGCI_LINT) run $(pkgs)
-endif
+	$(GO) list -e -compiled -test=true -export=false -deps=true -find=false -tags= -- ./... > /dev/null
+	$(GOLANGCI_LINT) run $(GOLANGCI_LINT_OPTS) $(pkgs)
 endif
 
 .PHONY: common-yamllint
@@ -218,28 +184,15 @@ endif
 common-staticcheck: lint
 
 .PHONY: common-unused
-common-unused: $(GOVENDOR)
-ifdef GOVENDOR
-	@echo ">> running check for unused packages"
-	@$(GOVENDOR) list +unused | grep . && exit 1 || echo 'No unused packages'
-else
-ifdef GO111MODULE
+common-unused:
 	@echo ">> running check for unused/missing packages in go.mod"
-	GO111MODULE=$(GO111MODULE) $(GO) mod tidy
-ifeq (,$(wildcard vendor))
+	$(GO) mod tidy
 	@git diff --exit-code -- go.sum go.mod
-else
-	@echo ">> running check for unused packages in vendor/"
-	GO111MODULE=$(GO111MODULE) $(GO) mod vendor
-	@git diff --exit-code -- go.sum go.mod vendor/
-endif
-endif
-endif
 
 .PHONY: common-build
 common-build: promu
 	@echo ">> building binaries"
-	GO111MODULE=$(GO111MODULE) $(PROMU) build --prefix $(PREFIX) $(PROMU_BINARIES)
+	$(PROMU) build --prefix $(PREFIX) $(PROMU_BINARIES)
 
 .PHONY: common-tarball
 common-tarball: promu
@@ -295,12 +248,6 @@ $(GOLANGCI_LINT):
 		| sh -s -- -b $(FIRST_GOPATH)/bin $(GOLANGCI_LINT_VERSION)
 endif
 
-ifdef GOVENDOR
-.PHONY: $(GOVENDOR)
-$(GOVENDOR):
-	GOOS= GOARCH= $(GO) get -u github.com/kardianos/govendor
-endif
-
 .PHONY: precheck
 precheck::