Cleanup of java.time serialization source

Serialization cleanup is needed.

HijrahChronology mixes "final transient" and "transient final". They
should be consistently one way or the other files should be checked.

Some classes have had transient added, while others haven't. For
example LocalDate doesn't use transient. Since the instance fields are
never directly serialized, but do appear in the serialized form,
perhaps they should be marked as transient?

The OffsetTime and OffsetDateTime classes have inconsistent serialization.
The serialized form will be more compact if they call writeExternal for dateTime, time,
and offset as is done in the other classes in java.time.

The byte code numbers for MinguoDate and ThaiBuddhistDate are now out
of line as you removed the ERA constants in Ser.

See /java/lang/reflect/Modifier.html#toString(int) for the conventional ordering of modifiers.
"public protected private abstract static final transient volatile synchronized native strictfp interface"