[ObjC] Simplify root registry generation.

The the distinction in the output isn't worth it.

PiperOrigin-RevId: 556828871

objectivec/GPBWrappers.pbobjc.m

diff --git a/objectivec/GPBWrappers.pbobjc.m b/objectivec/GPBWrappers.pbobjc.m
index 07be68b..bf5a8e1 100644
--- a/objectivec/GPBWrappers.pbobjc.m
+++ b/objectivec/GPBWrappers.pbobjc.m
@@ -36,8 +36,8 @@
 
 @implementation GPBWrappersRoot
 
-// No extensions in the file and no imports, so no need to generate
-// +extensionRegistry.
+// No extensions in the file and no imports or none of the imports (direct or
+// indirect) defined extensions, so no need to generate +extensionRegistry.
 
 @end