Fix out-of-bounds memory access in gemm_beta
Fix out-of-bounds memory access in gemm_beta

Fixes #2011 (as suggested by davemq), assuming typo by K.Goto
xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS