rb_provide_feature: Prevent $LOADED_FEATURES from being copied

	[Bug #18599]

	`vm->loaded_features` and `vm->loaded_features_snapshot` both share the
	same root. When a feature is pushed into `loaded_features`, the sharing
	is broken and `loaded_features` is copied.

	So an application requiring 1000 files, will allocate 1000 arrays of
	increasing size, which is very wasteful.

	To avoid this, we first clear the snapshot, so that `loaded_features`
	can directly be pushed into.

Co-Authored-By: Peter Zhu <peter.zhu@shopify.com>
	---
	 load.c | 4 ++++
	 1 file changed, 4 insertions(+)