Add rlib support for vendor_snapshot/update.py

Adds support for collecting rlibs as part of the vendor snapshot.

Bug: 184042776
Test: m dist vendor-snapshot
Test: python3 development/vendor_snapshot/update.py --local $DIST_DIR --install-dir
    vendor/vendor_name/vendor_snapshot VER
Test: vendor_snapshot_rlib modules generated, vendor_snapshot has rlibs
Change-Id: Ia90e53131c4ffba32883718b66ba99f4962d4633
diff --git a/vendor_snapshot/update.py b/vendor_snapshot/update.py
index 9a4bb26..0e14005 100644
--- a/vendor_snapshot/update.py
+++ b/vendor_snapshot/update.py
@@ -291,6 +291,7 @@
     variant_to_property = {
         'shared': 'shared_libs',
         'static': 'static_libs',
+        'rlib': 'rlibs',
         'header': 'header_libs',
         'binary': 'binaries',
         'object': 'objects',