Cannot configure a project against ITK with ITK_USE_GPU

When ITK is built with `ITK_USE_GPU`, configuring a project against it fails.

### Description

### Steps to Reproduce

A simple project defined by:
```cmake
project(tester CXX)
find_package(ITK REQUIRED)
itk_generate_factory_registration()
add_executable(tester tester.cpp)
target_link_libraries(tester ${ITK_INTERFACE_LIBRARIES} ITK::ITKImageIO)
```
fails to configure.

### Expected behavior

No errors.

### Actual behavior

```none
Selecting Windows SDK version 10.0.26100.0 to target Windows 10.0.26200.
Configuring done (0.1s)
CMake Error at C:/Misc/ITK-patches-dev-26/ITKTargets.cmake:1411 (set_target_properties):
The link interface of target "ITK::ITKGPUCommon" contains:

OpenCL::OpenCL

but the target was not found. Possible reasons include:

* There is a typo in the target name.
* A find_package call is missing for an IMPORTED target.
* An ALIAS target is missing.

Call Stack (most recent call first):
C:/Misc/ITK-patches-dev-26/ITKConfig.cmake:77 (include)
CMakeLists.txt:15 (find_package)

CMake Error at C:/Misc/ITK-patches-dev-26/ITKTargets.cmake:1421 (set_target_properties):
The link interface of target "ITK::ITKGPUCommonModule" contains:

OpenCL::OpenCL

but the target was not found. Possible reasons include:

* There is a typo in the target name.
* A find_package call is missing for an IMPORTED target.
* An ALIAS target is missing.

Call Stack (most recent call first):
C:/Misc/ITK-patches-dev-26/ITKConfig.cmake:77 (include)
CMakeLists.txt:15 (find_package)

Generating done (0.2s)
```

### Versions

`main` branch.

### Environment

CMake 4.4.0, Windows, latest Visual Studio 2026.

### Additional Information

OpenCL libraries are normally found:

Reproduce the failure with the provided CMakeLists.txt while ITK_USE_GPU is enabled. Inspect ITKConfig.cmake and the generated ITKTargets.cmake entries for ITK::ITKGPUCommon and ITK::ITKGPUCommonModule, focusing on their OpenCL::OpenCL link dependency. Done means the sample project configures without missing-target errors.

Written by the indexing model from the issue text.