Added cross compiling for Mac.

Makefile

@@ -14,6 +14,9 @@ LINTER=~/go/bin/linux_amd64/golangci-lint
 all:
 	$(GO) build -o bin .
 	$(GO) build -o bin/ackley_nogfx  -tags no_gfx --  .
+	GOOS=darwin GOARCH=amd64 $(GO) build -o bin/ackley_darwinamd64_nogfx -tags no_gfx -- .
+	GOOS=darwin GOARCH=arm64 $(GO) build -o bin/ackley_darwinarm64_nogfx -tags no_gfx -- .
+	GOOS=windows GOARCH=amd64 $(GO) build -o bin/ackley_win_nogfx -tags no_gfx -- .
 
 test:
 	$(GO) test ./...