[subset] Add hb_ot_layout_collect_features to harfbuzz-sections.txt.
Add the fuzzer test case for feature collection timeout.

docs/harfbuzz-sections.txt

diff --git a/docs/harfbuzz-sections.txt b/docs/harfbuzz-sections.txt
index b93cd1d..5cf5a88 100644
--- a/docs/harfbuzz-sections.txt
+++ b/docs/harfbuzz-sections.txt
@@ -447,6 +447,7 @@
 HB_OT_TAG_GSUB
 HB_OT_TAG_JSTF
 hb_ot_layout_collect_lookups
+hb_ot_layout_collect_features
 hb_ot_layout_feature_get_lookups
 hb_ot_layout_feature_with_variations_get_lookups
 hb_ot_layout_get_attach_points