Keep proguard fields for lite runtime of jarjared class

Some targets rename protobuf.MessageLite with jarjar rules. This change
adds keep rules to keep the fields of renamed classes.

Bug: 233746531
Test: m checkbuild.
Change-Id: Ib487dbd35f69654489aa28577afb47b9fb87c6f6
Merged-In: I986f05455b45651749fb5f819661041d7399f683

core/proguard_basic_keeps.flags

@@ -74,5 +74,6 @@
 -dontnote
 
 # The lite proto runtime uses reflection to access fields based on the names in
-# the schema, keep all the fields.
--keepclassmembers class * extends com.google.protobuf.MessageLite { <fields>; }
+# the schema, keep all the fields. Wildcard is used to apply the rule to classes
+# that have been renamed with jarjar.
+-keepclassmembers class * extends **.protobuf.MessageLite { <fields>; }