DYNAMIC_ARCH builds CORTEXA72 as a separate kernel and pull
dneg_tcopy from generic/neg_tcopy_$(DGEMM_UNROLL_M).c. Width 6 was
missing (only 1/2/4/8/16 existed), which broke the arm64 Graviton
Cirun and Azure DYNAMIC_ARM64 jobs.
Co-authored-by: Cursor <cursoragent@cursor.com>
