[mlir] [NFC] Add a newline to debug message at inserting of InterfaceMap

[sotoshigoto]

Summary

At inserting of InterfaceMap, a debug message lacked a newline, so it repeatedly displayed this message within a single line.
Clean up the debug log by inserting a newline at the end of the message.

[sotoshigoto]

@rriddle I don't have a commit access, could you land it?

mlir/lib/Support/InterfaceSupport.cpp

 
 void detail::InterfaceMap::insert(TypeID interfaceId, void *conceptImpl) {
   // Insert directly into the right position to keep the interfaces sorted.
   auto *it =
       llvm::lower_bound(interfaces, interfaceId, [](const auto &it, TypeID id) {
         return compare(it.first, id);
       });
   if (it != interfaces.end() && it->first == interfaceId) {
-    LLVM_DEBUG(llvm::dbgs() << "Ignoring repeated interface registration");
+    LLVM_DEBUG(llvm::dbgs() << "Ignoring repeated interface registration\n");
     free(conceptImpl);
     return;
   }
   interfaces.insert(it, {interfaceId, conceptImpl});
 }