Make upb's `WORKSPACE` point to local protobuf in the same Git repo

We plan to unify protobuf and upb into a single Bazel repo, but for now they
are separate repos as far as Bazel is concerned. This change will make upb's
workspace depend on the local copy of protobuf so that protobuf changes take
effect immediately for builds inside upb's workspace. This also mimicks the way
that the protobuf workspace depends on upb.

PiperOrigin-RevId: 560188433

upb/WORKSPACE

@@ -3,6 +3,11 @@ workspace(name = "upb")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("//bazel:workspace_deps.bzl", "upb_deps")
 
+local_repository(
+    name = "com_google_protobuf",
+    path = "..",
+)
+
 upb_deps()
 
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")

upb/cmake/make_cmakelists.py

@@ -306,6 +306,9 @@ class WorkspaceFileFunctions(object):
   def googletest_deps(self):
     pass
 
+  def local_repository(self, **kwargs):
+    pass
+
 
 class Converter(object):
   def __init__(self):