llama.cpp b9861 release with cpp-httplib update

The llama.cpp project has released version b9861, which includes a vendor update to cpp-httplib 0.49.0.

• macOS Apple Silicon (arm64) and Intel (x64) binaries are available.
• iOS XCFramework is provided for mobile deployment.
• Ubuntu builds support CPU, Vulkan, ROCm 7.2, OpenVINO, and SYCL FP32/FP16.
• Android arm64 (CPU) binaries are included.
• Windows builds cover CPU, CUDA 12/13, Vulkan, OpenVINO, SYCL, and HIP.
• openEuler support includes x86 and aarch64 variants with ACL Graph.

This release provides updated precompiled binaries for various hardware accelerators and operating systems.