Normalize native protoc path handling

contrib/build-linux-wallet.sh

@@ -33,7 +33,20 @@ reset_qt_configure_state() {
 }
 
 ensure_native_protoc() {
-  local found
+  local archive found
+
+  if [[ -x "$PROTOC" ]]; then
+    return 0
+  fi
+
+  archive="$(find "$ROOT/depends/built/$HOST/native_protobuf" \
+    -name 'native_protobuf-*.tar.gz' -type f 2>/dev/null | sort | tail -n 1 || true)"
+
+  if [[ -n "$archive" ]]; then
+    echo "Extracting native protoc from $archive"
+    mkdir -p "$ROOT/depends/build/$BUILD_HOST"
+    tar -xzf "$archive" -C "$ROOT/depends/build/$BUILD_HOST" ./bin/protoc
+  fi
 
   if [[ -x "$PROTOC" ]]; then
     return 0

depends/Makefile

@@ -114,6 +114,11 @@ ifneq ($(native_packages),)
 	  echo "  - $$p: $$f"; \
 	  tar -xzf $$f -C "$(build_prefix)"; \
 	done
+	@if [[ " $(native_packages) " == *" native_protobuf "* ]] && [[ ! -x "$(build_prefix)/bin/protoc" ]]; then \
+	  echo "ERROR: missing native protoc under $(build_prefix)/bin/protoc"; \
+	  echo "Fix: make -C $(BASEDIR) HOST=$(HOST) NO_QT=$(NO_QT) native_protobuf"; \
+	  exit 1; \
+	fi
 endif
 	@echo "== Writing config.site: $(host_prefix)/share/config.site"
 	@mkdir -p "$(host_prefix)/share"