hashmap: provide deallocation function names

hashmap_free(), hashmap_free_entries(), and hashmap_free_() have existed
for a while, but aren't necessarily the clearest names, especially with
hashmap_partial_clear() being added to the mix and lazy-initialization
now being supported.  Peff suggested we adopt the following names[1]:

  - hashmap_clear() - remove all entries and de-allocate any
    hashmap-specific data, but be ready for reuse

  - hashmap_clear_and_free() - ditto, but free the entries themselves

  - hashmap_partial_clear() - remove all entries but don't deallocate
    table

  - hashmap_partial_clear_and_free() - ditto, but free the entries

This patch provides the new names and converts all existing callers over
to the new naming scheme.

[1] https://lore.kernel.org/git/20201030125059.GA3277724@coredump.intra.peff.net/

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/range-diff.c b/range-diff.c
index 24dc435..befeeca 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -266,7 +266,7 @@ static void find_exact_matches(struct string_list *a, struct string_list *b)
 		}
 	}
 
-	hashmap_free(&map);
+	hashmap_clear(&map);
 }
 
 static void diffsize_consume(void *data, char *line, unsigned long len)