Add Update method for the cpuset controller

[anastop]

So that the CPUs and memory nodes of a cgroup can be dynamically changed.

[codecov-io]

Codecov Report

Merging #45 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master      #45      +/-   ##
==========================================
- Coverage   13.12%   13.12%   -0.01%     
==========================================
  Files          23       23              
  Lines        4494     4496       +2     
==========================================
  Hits          590      590              
- Misses       3792     3794       +2     
  Partials      112      112

Impacted Files	Coverage Δ
cpuset.go	41.97% <0%> (-1.07%)	⬇️

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[crosbymichael]

Have you tried this out to see if it works or if there were any side effects?

[anastop]

I have tried this in my case (dynamic process CPU rescheduling) and it works as expected, that is, processes migrate to the new cpuset's CPUs. Unfortunately, my test environment (single-NUMA node) does not allow me to test cpuset.mems. Other than this, are there particular test cases I could run to see possible side effects?

[crosbymichael]

@anastop can you sign your commit with the DCO ?

[anastop]

should be ok now

[estesp]

LGTM

[crosbymichael]

LGTM