build: apply rpctest tag in itest

We need to distinguish an lnd build for the purpose of integration
testing from a regular dev build. This makes it possible to adapt
parameters to let integration tests run faster (for example:
sweeper batch window).

Makefile

@@ -100,6 +100,11 @@ build:
 	$(GOBUILD) -tags="$(DEV_TAGS)" -o lnd-debug $(LDFLAGS) $(PKG)
 	$(GOBUILD) -tags="$(DEV_TAGS)" -o lncli-debug $(LDFLAGS) $(PKG)/cmd/lncli
 
+build-itest:
+	@$(call print, "Building itest lnd and lncli.")
+	$(GOBUILD) -tags="$(ITEST_TAGS)" -o lnd-itest $(LDFLAGS) $(PKG)
+	$(GOBUILD) -tags="$(ITEST_TAGS)" -o lncli-itest $(LDFLAGS) $(PKG)/cmd/lncli
+
 install:
 	@$(call print, "Installing lnd and lncli.")
 	$(GOINSTALL) -tags="${tags}" $(LDFLAGS) $(PKG)
@@ -118,7 +123,7 @@ itest-only:
 	@$(call print, "Running integration tests.")
 	$(ITEST)
 
-itest: btcd build itest-only
+itest: btcd build-itest itest-only
 
 unit: btcd
 	@$(call print, "Running unit tests.")
@@ -181,6 +186,7 @@ rpc:
 clean:
 	@$(call print, "Cleaning source.$(NC)")
 	$(RM) ./lnd-debug ./lncli-debug
+	$(RM) ./lnd-itest ./lncli-itest
 	$(RM) -r ./vendor .vendor-new