Never attempt to build protocol buffers offline

Building protocol buffers requires fetching utilities from the
Internet. Typically this is done at development time and the finished
buffers are included in dist; but if timestamps get off this can lead
mock to try to rebuild them during an offline build, causing the build
to fail.

This change moves all of the protoc targets into a section of the
Makefile that is disabled during an offline build.

- Closes #1155

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

Makefile

@@ -160,25 +160,6 @@ reference: wwctl
 
 latexpdf: reference
 	make -C userdocs latexpdf
-protofiles = internal/pkg/api/routes/wwapiv1/routes.pb.go \
-	internal/pkg/api/routes/wwapiv1/routes.pb.gw.go \
-	internal/pkg/api/routes/wwapiv1/routes_grpc.pb.go
-.PHONY: proto
-proto: $(protofiles)
-
-routes_proto = internal/pkg/api/routes/v1/routes.proto
-$(protofiles): $(routes_proto)
-	PATH=$(TOOLS_BIN):$(PATH) $(PROTOC) \
-		-I /usr/include -I $(shell dirname $(routes_proto)) -I=. \
-		--grpc-gateway_opt logtostderr=true \
-		--go_out=. \
-		--go-grpc_out=. \
-		--grpc-gateway_out=. \
-		routes.proto
-
-.PHONY: cleanproto
-cleanproto:
-	rm -f $(protofiles)
 
 .PHONY: cleanconfig
 cleanconfig:
@@ -231,7 +212,25 @@ dist: vendor
 
 lint: $(GOLANGCI_LINT)
 
-$(protofiles): $(PROTOC) $(PROTOC_GEN_GRPC_GATEWAY) $(PROTOC_GEN_GO) $(PROTOC_GEN_GO_GRPC)
+protofiles = internal/pkg/api/routes/wwapiv1/routes.pb.go \
+	internal/pkg/api/routes/wwapiv1/routes.pb.gw.go \
+	internal/pkg/api/routes/wwapiv1/routes_grpc.pb.go
+.PHONY: proto
+proto: $(protofiles)
+
+routes_proto = internal/pkg/api/routes/v1/routes.proto
+$(protofiles): $(routes_proto) $(PROTOC) $(PROTOC_GEN_GRPC_GATEWAY) $(PROTOC_GEN_GO) $(PROTOC_GEN_GO_GRPC)
+	PATH=$(TOOLS_BIN):$(PATH) $(PROTOC) \
+		-I /usr/include -I $(shell dirname $(routes_proto)) -I=. \
+		--grpc-gateway_opt logtostderr=true \
+		--go_out=. \
+		--go-grpc_out=. \
+		--grpc-gateway_out=. \
+		routes.proto
+
+.PHONY: cleanproto
+cleanproto:
+	rm -f $(protofiles)
 
 clean: cleanvendor
 endif