utf8_heavy.pl: Change data structure for in-lined definitions

utf8_heavy.pl: Change data structure for in-lined definitions

This commit puts the in-lined definitions introduced by
eb0925341cc65ce6ce57503ec0ab97cdad39dc98 into a separate array,
where each element is a unique definition.  This can result in slightly
smaller current memory usage in utf8_heavy.pl, as the strings giving the
file names now only appear once, and what replaces them in the hash
values are strings of digits indices, which are shorter.

But doing this allows us in a later commit to increase the number of
ranges in the tables that get in-lined, without increasing memory usage.

This commit also changes the code that generates the definitions to be
more general, so that it becomes trivial to change things to generate
in-line definitions for tables with more than one range.