func_cache: add space upgrade func holder type

Online space upgrade applies a function to all tuples in a space.
The function should be pinned so we need a new holder type.

Follow-up commit 38b25832 ("box: add space upgrade stubs").

NO_DOC=internal
NO_TEST=internal
NO_CHANGELOG=internal

(cherry picked from commit 98bb3bd4)

src/box/func_cache.c

@@ -14,7 +14,8 @@ static struct mh_i32ptr_t *funcs;
 static struct mh_strnptr_t *funcs_by_name;
 
 const char *func_cache_holder_type_strs[FUNC_HOLDER_MAX] = {
-	"constraint",
+	[FUNC_HOLDER_CONSTRAINT] = "constraint",
+	[FUNC_HOLDER_SPACE_UPGRADE] = "space upgrade",
 };
 
 void

src/box/func_cache.h

@@ -19,6 +19,7 @@ struct func;
  */
 enum func_holder_type {
 	FUNC_HOLDER_CONSTRAINT,
+	FUNC_HOLDER_SPACE_UPGRADE,
 	FUNC_HOLDER_MAX,
 };