There are systems where the size file does not exist. Most badly even
lscpu -p would abort allthough it does not use the size:
$ lscpu -p
lscpu: error: cannot open
/sys/devices/system/cpu/cpu0/cache/index0/size: No such file or directory
This patch does not abort in this case and prints "unknown size" in
human-readable case. For examle on this qemu pcc test machine:
$ lscpu
Architecture: ppc
CPU op-mode(s): 32-bit
Byte Order: Big Endian
CPU(s): 1
On-line CPU(s) list: 0
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 1
Model: Power Macintosh
BogoMIPS: 33.25
L1d cache: unknown size
L1i cache: unknown size