Handle shmem init failures in cpu affinity setup code
Handle shmem init failures in cpu affinity setup code

Failures to obtain or attach shared memory segments would lead to an exit without explanation of the exact cause.
This change introduces a more verbose error message and tries to make the code continue without setting cpu affinity.
Fixes #1351
kortschak/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS