Fix decoding of overencoded booleans.
Fix decoding of overencoded booleans.

if the value was >32bit with the low bits all being zero, it was decoded as
false instead of as true.

Fixes #6863

google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf