v2.6

• Introduce a DMA-BUF mmap backend for mapping GPU memory without the GDRCopy kernel module. GDRCopy still prefers gdrdrv when available, can fall back to DMA-BUF mmap with CUDA driver 13.3+, and can force the new backend with GDRCOPY_USE_DMABUF_MMAP.
• Introduce GDR_ATTR_USING_DMA_BUF_MMAP so applications can query whether GDRCopy is using the DMA-BUF mmap backend.
• Improve gdr_copy_to_mapping and gdr_copy_from_mapping performance with runtime-selected CPU copy implementations for AVX2, AVX-512, MOVDIR64B, NEON, and LS64-capable systems.
• Add -M to gdrcopy_apiperf, gdrcopy_copybw, gdrcopy_copylat, and gdrcopy_pplat to request default, WC, cache, or device mappings.
• Change gdrcopy_copylat and gdrcopy_pplat to report P0 and P50 latency metrics instead of average latency.
• Fix build and install errors on Ubuntu 25.10 by using numeric install modes and dropping deprecated depmod -r usage.