spellcheck: support transpositions aka Damerau-Levenshtein (PR other/69968)

spellcheck: support transpositions aka Damerau-Levenshtein (PR other/69968)

gcc/fortran/ChangeLog:
	PR other/69968
	* misc.c (gfc_closest_fuzzy_match): Update for renaming of
	levenshtein_distance to get_edit_distance.

gcc/ChangeLog:
	PR other/69968
	* spellcheck-tree.c (levenshtein_distance): Rename to...
	(get_edit_distance): ...this, and update for underlying renaming.
	* spellcheck-tree.h (levenshtein_distance): Rename to...
	(get_edit_distance): ...this.
	* spellcheck.c (levenshtein_distance): Rename to...
	(get_edit_distance): ...this.  Convert from Levenshtein distance
	to Damerau-Levenshtein distance by supporting transpositions of
	adjacent characters.  Rename "v1" to "v_next" and "v0" to
	"v_one_ago".
	(selftest::levenshtein_distance_unit_test_oneway): Rename to...
	(selftest::test_edit_distance_unit_test_oneway): ...this, and
	update for underlying renaming.
	(selftest::levenshtein_distance_unit_test): Rename to...
	(selftest::test_get_edit_distance_unit): ...this, and update for
	underlying renaming.
	(selftest::test_find_closest_string): Add example from PR 69968
	where transposition helps
	(selftest::test_metric_conditions): Update for renaming.
	(selftest::test_metric_conditions): Likewise.
	(selftest::spellcheck_c_tests): Likewise.
	* spellcheck.h (levenshtein_distance): Rename both overloads to...
	(get_edit_distance): ...this.
	(best_match::consider): Update for renaming.

gcc/testsuite/ChangeLog:
	PR other/69968
	* gcc.dg/spellcheck-transposition.c: New test.

From-SVN: r261521