reintroduce rule to cross-build a linux binary (#7334)

closes: #7333

Author: Alessio Treglia

Makefile

@@ -90,6 +90,9 @@ simd:
 	mkdir -p $(BUILDDIR)
 	go build -mod=readonly $(BUILD_FLAGS) -o $(BUILDDIR) ./simapp/simd
 
+simd-linux: go.sum
+	$(MAKE) simd GOOS=linux GOARCH=amd64 LEDGER_ENABLED=false
+
 build-simd-all: go.sum
 	$(if $(shell docker inspect -f '{{ .Id }}' cosmossdk/rbuilder 2>/dev/null),$(info found image cosmossdk/rbuilder),docker pull cosmossdk/rbuilder:latest)
 	docker rm latest-build || true
@@ -433,7 +436,7 @@ proto-update-deps:
 ###############################################################################
 
 # Run a 4-node testnet locally
-localnet-start: build-simd-linux localnet-stop
+localnet-start: $(BUILDDIR)/simd localnet-stop
 	$(if $(shell docker inspect -f '{{ .Id }}' cosmossdk/simd-env 2>/dev/null),$(info found image cosmossdk/simd-env),$(MAKE) -C contrib/images simd-env)
 	if ! [ -f build/node0/simd/config/genesis.json ]; then docker run --rm \
 		--user $(shell id -u):$(shell id -g) \