[x265] CLI: new logic for '--pools <int>' option

[Mateusz]

 > Using numNumaNodes * MAX_POOL_THREADS as the upper-bound on the # 
threads per numa node isn't the cleanest.

My intention was to use the upper-bound for whole threads number (on all 
NUMAs).

This patch is only for case '--pools N' where N is a number, for example 
'--pools 55' create exactly 55 threads (with affinity for all logical 
CPUs on all NUMAs). Old logic for '--pools 55' was to create min(55, 
#CPU on NUMA 0) threads on NUMA 0 and 0 threads on all remaining NUMAs. 
To use old logic with this patch you can add comma: '--pools 55,'

If I use '--pools 6144 -F16' option with this patch on i5 CPU, I get
x265 [info]: Thread pool created using 64 threads
x265 [info]: frame threads / pool features       : 16 / wpp(12 rows)

Without this patch I get only 4 threads.

 > Also, can you please include the patch as inline in future so that it 
becomes easier to review?

I will do that, thanks for info. My first attempt to do this fail due to 
line breaking in my e-mail client.