-keepclasses is not a proguard option

It looks like proguard is accepting it and make completion to a valid
option even if there's ambiguity beetwen -keepclasseswithmembers and
-keepclasseswithmembernames. Jack is not permitting that kind of
incomplete options, so fixing.

Change-Id: I034e1cb6ecdcd96beec11ac6b30a0baeb1aebba3
1 file changed