Fix -Wunreachable-code-break findings in fbcode/executorch, xplat/executorch

Summary:
D127334907 enables `-Wunreachable-code-break` through the PACKAGE files of `fbcode/example`, `fbcode/excalibur`, `fbcode/executorch`, `fbcode/experience-ai`, `xplat/executorch`. This diff fixes the code that warning flags there, so the PACKAGE change builds cleanly on top of it.

Fixes the new warning in executorch (fbcode side edited; the `xplat/executorch` dirsync mirror is identical): removes `break;` statements that can never run because the preceding statement always leaves the case. In `devtools/bundled_program/bundled_program.cpp` they follow `ET_CHECK_OR_RETURN_ERROR(false, ...)` (always returns) or `return`; in `extension/fb/ptez/ptez_data_loader.cpp` and `runtime/executor/method_meta.cpp` (`get_tag`) they follow `return`; in `backends/vulkan/runtime/vk_api/Pipeline.cpp` (`vk_layout`) the inner `switch` returns on every path. Behavior is unchanged.

Removes unreachable `break;` statements in Vulkan test and tool code (fbcode side edited; the `xplat/executorch` mirror is identical): `backends/vulkan/test/utils/test_utils.cpp` (after `throw`), `backends/vulkan/test/vulkan_compute_api_test.cpp` (after an inner `switch` that returns on every path), and `backends/vulkan/fb/tools/cli/{benchmark,correctness}/optparser.cpp` (after `exit(1)`).

Reviewed By: dtolnay

Differential Revision: D127368223

Pull Request resolved: pytorch#24155

Author: r-barnes

backends/vulkan/runtime/vk_api/Pipeline.cpp

@@ -82,7 +82,6 @@ VkImageLayout vk_layout(
         default:
           return VK_IMAGE_LAYOUT_GENERAL;
       }
-      break;
     case PipelineStage::TRANSFER:
       switch (access) {
         case MemoryAccessType::READ:

backends/vulkan/test/utils/test_utils.cpp

@@ -340,7 +340,6 @@ void record_index_fill_buffer(api::Context* context, api::vTensor& v_ten) {
       break;
     default:
       throw std::runtime_error("Unsupported dtype");
-      break;
   }
 
   api::ParamsBuffer params(api::context(), int32_t(v_ten.numel()));

backends/vulkan/test/vulkan_compute_api_test.cpp

@@ -292,7 +292,6 @@ std::vector<int64_t> get_reference_strides(
         default:
           return {};
       }
-      break;
     case utils::kHeightPacked:
       switch (sizes.size()) {
         case 1:

devtools/bundled_program/bundled_program.cpp

@@ -338,7 +338,6 @@ ET_NODISCARD Error load_bundled_input(
             NotSupported,
             "Data type %hhu not supported",
             static_cast<uint8_t>(bundled_input->val_type()));
-        break;
       }
     }
 
@@ -450,7 +449,6 @@ ET_NODISCARD ErrorStats compute_method_output_error_stats(
             "Data type %hhd not supported",
             static_cast<uint8_t>(bundled_expected_output->val_type()));
         return {Error::NotSupported, 0, 0, 0, 0};
-        break; // Never reached
       }
     }
   }
@@ -532,7 +530,6 @@ ET_NODISCARD Error verify_method_outputs(
             NotSupported,
             "Data type %hhd not supported",
             static_cast<uint8_t>(bundled_expected_output->val_type()));
-        break;
       }
     }
   }

runtime/executor/method_meta.cpp

@@ -96,22 +96,22 @@ Result<Tag> get_tag(
   switch (serialization_value->val_type()) {
     case executorch_flatbuffer::KernelTypes::Null: {
       return Tag::None;
-    } break;
+    }
     case executorch_flatbuffer::KernelTypes::Int: {
       return Tag::Int;
-    } break;
+    }
     case executorch_flatbuffer::KernelTypes::Double: {
       return Tag::Double;
-    } break;
+    }
     case executorch_flatbuffer::KernelTypes::Bool: {
       return Tag::Bool;
-    } break;
+    }
     case executorch_flatbuffer::KernelTypes::String: {
       return Tag::String;
-    } break;
+    }
     case executorch_flatbuffer::KernelTypes::Tensor: {
       return Tag::Tensor;
-    } break;
+    }
     default:
       ET_LOG(
           Error,