Makefile: Fix darwin name

Author: lazyfrosch

Makefile

@@ -16,7 +16,7 @@ build:
 	GOOS=linux   GOARCH=amd64 $(GO_BUILD) -o build/$(NAME)-linux-amd64 .
 	GOOS=linux   GOARCH=386   $(GO_BUILD) -o build/$(NAME)-linux-i386 .
 	GOOS=windows GOARCH=amd64 $(GO_BUILD) -o build/$(NAME)-windows-amd64.exe .
-	GOOS=darwin  GOARCH=amd64 $(GO_BUILD) -o build/$(NAME)-darwin-amd64.exe .
+	GOOS=darwin  GOARCH=amd64 $(GO_BUILD) -o build/$(NAME)-darwin-amd64 .
 
 test:
 	go test -v ./...