gen-options.awk: Add a more compact data representation.

gen-options.awk: Add a more compact data representation.

Add a new set of macros that can be used to encode the long options
array as integers, which is possible provided that the "action"
feature is not used.  In addition to reducing the size of the
static array, it should be helpful to avoid relocations in
position-independent executables and improve data sharing.