Makefile: build proto files unconditionally

Ditch the makefile pattern rule which simply doesn't work in scenarios
where both the source and the build targets are stored in the git repo
(as git operations mangle the time stamps).

So much grey hair avoided when the stuff just force generates
everything instead of leaving you wonder why the tools didn't work as
expected.

Signed-off-by: Markus Lehtonen <markus.lehtonen@intel.com>

Makefile

@@ -36,7 +36,6 @@ COVERAGE_PATH := $(BUILD_PATH)/coverage
 
 PROTOBUF_VERSION = 3.20.1
 PROTO_SOURCES = $(shell find pkg -name '*.proto' | grep -v /vendor/)
-PROTO_GOFILES = $(patsubst %.proto,%.pb.go,$(PROTO_SOURCES))
 PROTO_INCLUDE = -I $(PWD) -I$(PROTOC_PATH)/include
 PROTO_OPTIONS = --proto_path=. $(PROTO_INCLUDE) \
     --go_opt=paths=source_relative --go_out=. \
@@ -80,11 +79,15 @@ FORCE:
 # build targets
 #
 
-build-proto: check-protoc install-ttrpc-plugin install-wasm-plugin install-protoc-dependencies $(PROTO_GOFILES)
+build-proto: check-protoc install-ttrpc-plugin install-wasm-plugin install-protoc-dependencies
+	for src in $(PROTO_SOURCES); do \
+		$(PROTO_COMPILE) $$src; \
+	done
+	sed -i '1s;^;//go:build !wasip1\n\n;' pkg/api/api_ttrpc.pb.go
 
 .PHONY: build-proto-dockerized
 build-proto-dockerized:
-	$(Q)docker build --build-arg ARTIFACTS="$(dir $(PROTO_GOFILES))" --target final \
+	$(Q)docker build --build-arg ARTIFACTS="$(dir $(PROTO_SOURCES))" --target final \
 		--output type=local,dest=$(RESOLVED_PWD) \
 		-f hack/Dockerfile.buildproto .
 	$(Q)tar xf artifacts.tgz && rm -f artifacts.tgz
@@ -176,15 +179,6 @@ validate-repo-no-changes:
 		exit 1; \
 	}
 
-#
-# proto generation targets
-#
-
-%.pb.go: %.proto
-	$(Q)echo "Generating $@..."; \
-	$(PROTO_COMPILE) $<
-	sed -i '1s;^;//go:build !wasip1\n\n;' pkg/api/api_ttrpc.pb.go
-
 #
 # targets for installing dependencies
 #