Improve API of recently-added bool vector functions.

Improve API of recently-added bool vector functions.

The old API had (bool-vector-count-matches A B)
and (bool-vector-count-matches-at A B I), which gave the
misleading impression that the two functions were variants, one
with a location I.  The new API has (bool-vector-count-population A)
and (bool-vector-count-consecutive A B I) to make the distinction
clearer.  The first function no longer has a B argument, since the
caller can easily determine the number of nils if the length and
number of ts is known.
* src/data.c (Fbool_vector_count_population): Rename from
bool_vector_count_matches, and accept just 1 argument.
(Fbool_vector_count_consecutive): Rename from
Fbool_vector_count_matches_at.
* test/automated/data-tests.el: Adjust to API changes.

Fixes: debbugs:15912