libxl: introduce libxl_cpupool_cpu{add, remove}_cpumap()

libxl: introduce libxl_cpupool_cpu{add, remove}_cpumap()

To add (removes) to (from) a cpupool all the pCPUs corresponding
to the bits that are set in the passed bitmap.

This is convenient and useful in order to implement, in xl,
the possibility of specifying ranges of pCPUs to be added
(removed) to (from) a cpupool, in the relevant commands.

While there, convert libxl_cpupool_cpu{add,remove} to use the
appropriate logging macro (LOGE()).

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Juergen Gross <JGross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>