remove unnecessary support for prebuilt binaries

the users will know how to build the binaries themselves.

Makefile

@@ -1,32 +1,15 @@
 SCRIPTS = $(shell awk '/#!\/bin\/(ba)?sh/&&FNR==1{print FILENAME}' $(shell git ls-files))
 GODEPS = $(shell git ls-files '*.go' go.mod go.sum)
-GOOSARCHS = $(sort darwin/amd64 linux/amd64)
 
 VSN ?= $(shell git describe --dirty)
 VSNHASH = $(shell git rev-parse --verify HEAD)
 LDFLAGS = -ldflags "-X main.Version=$(VSN) -X main.VersionHash=$(VSNHASH)"
 
 undocker: ## builds binary for the current architecture
-	CGO_ENABLED=0 go build $(LDFLAGS) -o $@
+	go build $(LDFLAGS) -o $@
 
 .PHONY: test
-test:
-	go test -race -cover ./...
-
-define undockertarget
-UNDOCKERS += undocker-$(1)-$(2)-$(VSN)
-undocker-$(1)-$(2)-$(VSN): $(GODEPS)
-	CGO_ENABLED=0 GOOS=$(1) GOARCH=$(2) go build $(LDFLAGS) -o $$@
-endef
-
-$(foreach goosarch,$(GOOSARCHS),\
-	$(eval $(call undockertarget,$(word 1,$(subst /, ,$(goosarch))),$(word 2,$(subst /, ,$(goosarch))))))
-
-.PHONY: all
-all: $(UNDOCKERS) sha256sum-$(VSN).txt
-
-.PHONY: sha256sum-asc
-sha256sum-asc: sha256sum-$(VSN).txt.asc
+test: coverage.out
 
 .PHONY: lint
 lint:
@@ -36,17 +19,11 @@ lint:
 
 .INTERMEDIATE: coverage.out
 coverage.out: $(GODEPS)
-	go test -coverprofile $@ ./...
+	go test -race -cover -coverprofile $@ ./...
 
 coverage.html: coverage.out
 	go tool cover -html=$< -o $@
 
-sha256sum-$(VSN).txt: $(UNDOCKERS)
-	sha256sum $(UNDOCKERS) > $@
-
-sha256sum-$(VSN).txt.asc: sha256sum-$(VSN).txt
-	gpg --clearsign $<
-
 .PHONY: clean
 clean:
-	rm -f undocker-*-v* coverage.html sha256sum*.txt sha256sum*.txt.asc
+	rm -f undocker-*-v* coverage.html