Roll-forward the VNDK snapshot list of GSI

The latest stable SDK version is 31, so add 31 to the list of VNDK
snapshots.

Bug: 196806844
Test: Presubmit
Change-Id: Ia9aab527d9c1fe1d1eb6c72ebc184a3fccad6a22
Merged-In: Ia9aab527d9c1fe1d1eb6c72ebc184a3fccad6a22
(cherry picked from commit 33fc244de578bf7d3c3ace902d1495b3dfe8967b)
diff --git a/target/product/gsi_release.mk b/target/product/gsi_release.mk
index 94917f5..aaeefcb 100644
--- a/target/product/gsi_release.mk
+++ b/target/product/gsi_release.mk
@@ -62,8 +62,12 @@
     init.gsi.rc \
     init.vndk-nodef.rc \
 
-# Support additional P, Q and R VNDK packages
-PRODUCT_EXTRA_VNDK_VERSIONS := 28 29 30
+# Support additional VNDK snapshots
+PRODUCT_EXTRA_VNDK_VERSIONS := \
+    28 \
+    29 \
+    30 \
+    31 \
 
 # Do not build non-GSI partition images.
 PRODUCT_BUILD_CACHE_IMAGE := false