reference fix for amzn/ion-c#292

diff --git a/ion-c b/ion-c
index 98e8043b58e310d3ca03928956c7ea6caed02c69..ab2aba07639fcc0707a4e95f2e9707a13e9fab0b 160000 (submodule)
--- a/ion-c
+++ b/ion-c
@@ -1 +1 @@
-Subproject commit 98e8043b58e310d3ca03928956c7ea6caed02c69
+Subproject commit ab2aba07639fcc0707a4e95f2e9707a13e9fab0b