Fixed regression in pre12 in crypto/munge when running with --enable-multiple-slurmd which would cause the slurmd's to core.

select/cray: remove forward declarations

This removes forward declarations by reordering the function definitions.

select: make argument of select_p_select_jobinfo_alloc() consistent

This explicitly declares the argument list of select_p_select_jobinfo_alloc()
to be 'void', to avoid misinterpreting it as an old-style definition:
 * node_select.h already defines select_g_select_jobinfo_alloc(void);
 * the cons_res variant erroneously specified 'select_jobinfo_t *jobinfo';
 * explicit argument list makes bug tracking easier.

There were quite a few changes due to slurm changes from pre11 to pre12
and i also removed some void** function arguments.

select/cray: share the select_ops symbol table

This removes code duplication from the select/cray plugin, by 
 * sharing the (almost completely identical) declaration of the select_opts struct;
 * and also the slurm_select_context_t struct;
 * moving typedefs from .c into .h;
 * adjusting header-includes and renaming as required.

Further changes:
 * added the missing 'plugin_id' to the symbol list in other_select.c (otherwise
   the symbols would be shifted, causing segfault);
 * __select_jobinfo_t_defined is already set in slurm.h(.in), hence no longer
   repeated in node_select.h;
 * removed unused forward declarations to destroy the context.

  which we have the create function for

    libraries are not generally usable.