LU-6210 utils: Use C99 initializer in jt_nodemap_modify()

LU-6210 utils: Use C99 initializer in jt_nodemap_modify()

This patch makes no functional changes.  The long_options struct
initializer in jt_nodemap_modify() is updated to C99 syntax.
It is renamed to long_opts for consistency.

C89 positional initializers require values to be placed in the
correct order. This will cause errors if the fields of the struct
definition are reordered or fields are added or removed. C99 named
initializers avoid this problem, and also automatically clear any
values that are not explicitly set.

Test-Parameters: trivial
Signed-off-by: Steve Guminski <stephenx.guminski@intel.com>
Change-Id: I4c1bd5a3aa26c486436ae68d698fd89f8735a7fb
Reviewed-on: https://review.whamcloud.com/27889
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>