Merge branch '32-replace-margo-with-mercury-in-client-code' of ssh://bscssrg.bsc.es:2222/hpc/gekkofs into 32-replace-margo-with-mercury-in-client-code

Merge branch '43-improve-delete-performance-for-small-chunksize-nnodes-files' into '32-replace-margo-with-mercury-in-client-code'

Resolve "Improve delete performance for small files"

See merge request hpc/gekkofs!23

Fixes an issue where client applications such as ssh might attempt to
close all open fds, therefore also closing the fds used by the internal
components of the library such as Mercury.