Use one-dimension arrays in gen-posix-conf-vars.awk
True multi-dimensional arrays were introduced in awk 4.0 and we
support awk versions as early as 3.12. Use a single subscript of the
form prefix_conf instead of two dimensions to work around this
limitation. We also need one additional array of just the conf names
subscripted by the prefix_conf to print the names for the
specifications.
* scripts/gen-posix-conf-vars.awk: Don't use multi-dimensional
arrays.