llama.cpp b9988 release harmonizes test headers and provides binaries

The llama.cpp project has released version b9988, which includes a change to harmonize the use of private ggml includes in tests. This update ensures that the build process relies on shipped headers rather than potentially system-installed ones.

• Tests now use quoted includes in test-backend-ops to standardize header usage.
• macOS Apple Silicon builds with KleidiAI are disabled.
• Binaries are provided for Ubuntu (CPU, Vulkan, ROCm 7.2, OpenVINO, SYCL), Windows (CPU, CUDA 12/13, Vulkan, OpenVINO, SYCL, HIP), Android arm64, and iOS.

This release provides updated binaries across multiple platforms while addressing build consistency in the test suite.