Fix protoc include paths

After the target refactor, the relative protoc include paths collected
by GN are no longer correct. This change switches over to using absolute
paths.

Change-Id: Ib175c7149b422b279457b65d662a9122eeb35973
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/12602
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Alexei Frolov <frolv@google.com>
diff --git a/pw_protobuf_compiler/proto.gni b/pw_protobuf_compiler/proto.gni
index 13e2e67..09ebaa6 100644
--- a/pw_protobuf_compiler/proto.gni
+++ b/pw_protobuf_compiler/proto.gni
@@ -257,7 +257,7 @@
 
     # Indicate this library's base directory for its dependents.
     metadata = {
-      protoc_includes = [ rebase_path(".", root_out_dir) ]
+      protoc_includes = [ rebase_path(".") ]
     }
   }