build: leverage arch env variable in build

Makefile

@@ -2,7 +2,6 @@
 SHELL=/bin/bash -o pipefail
 
 .DEFAULT_GOAL:=help
-
 GOPATH  := $(shell go env GOPATH)
 GOARCH  := $(shell go env GOARCH)
 GOOS    := $(shell go env GOOS)
@@ -55,15 +54,15 @@ IMAGE_TAG := falcosecurity/falcosidekick:latest
 .PHONY: falcosidekick
 falcosidekick:
 	$(GO) mod download
-	$(GO) build -trimpath -ldflags "$(LDFLAGS)" -gcflags all=-trimpath=/src -asmflags all=-trimpath=/src -a -installsuffix cgo -o $@ .
+	GOOS=$(GOOS) GOARCH=$(GOARCH) $(GO) build -trimpath -ldflags "$(LDFLAGS)" -gcflags all=-trimpath=/src -asmflags all=-trimpath=/src -a -installsuffix cgo -o $@ .
 
-.PHONY: falcosidekick-linux-amd64
-falcosidekick-linux-amd64:
+.PHONY: falcosidekick-linux
+falcosidekick-linux:
 	$(GO) mod download
-	GOOS=linux GOARCH=amd64 $(GO) build -gcflags all=-trimpath=/src -asmflags all=-trimpath=/src -a -installsuffix cgo -o falcosidekick .
+	GOOS=linux GOARCH=$(GOARCH) $(GO) build -ldflags "$(LDFLAGS)" -gcflags all=-trimpath=/src -asmflags all=-trimpath=/src -a -installsuffix cgo -o falcosidekick .
 
 .PHONY: build-image
-build-image: falcosidekick-linux-amd64
+build-image: falcosidekick-linux
 	$(DOCKER) build -t $(IMAGE_TAG) .
 
 .PHONY: push-image