Warning fixes (sign mismatch), switch default

gemma/configs.h

@@ -107,6 +107,7 @@ static inline int AttentionImplToFlags(AttentionImpl impl,
     case AttentionImpl::kOld:
       return kAttentionUseOld;
     case AttentionImpl::kFlash:
+    default:
       return 0;
   }
 }

gemma/gemma.cc

@@ -628,7 +628,7 @@ static void GenerateTWithContinuousBatching(
   const SampleFunc sample_token =
       ChooseSampleFunc(runtime_config, engine, env.ctx);
 
-  int query_inserted = 0;
+  size_t query_inserted = 0;
   while (non_eos.Any() || query_inserted < all_queries.NumQueries()) {
     for (size_t qi = 0; qi < qbatch.Size(); ++qi) {
       // Continue if qi slot is still processing.

gemma/query.h

@@ -131,7 +131,7 @@ class QBatch {
     HWY_DASSERT(size_ != 0);
     HWY_DASSERT(start_ + size_ <= queries_.NumQueries());
     query_idx_.reserve(size_);
-    for (int i = 0; i < size_; ++i) {
+    for (size_t i = 0; i < size_; ++i) {
       query_idx_.push_back(start_ + i);
     }
   }