[threeten-dev] Move tzdb compiler out of j.t.z

[Xueming Shen]

Stephen,

Here is the webrev for moving the tzdb compiler out of j.t.z package.

http://cr.openjdk.java.net/~sherman/jdk8_threeten/tzc/

The approach here appears to cause a slower startup compared to the
existing one, as it uses ObjectOutput/InputStream directly to write out and
read in zrules, instead of the DateOutput/InputStream, in which the existing
impl can take advantage of the direct access to Ser to write out/read in
"byte[]" of the zrules, so the TzdbZoneRuleProvider can do lazy-init. The
compiler can't do it now because the Ser is package private.

The plan-B is to externalize the Ser.write/read to somewhere, so the byte[]
of the zrules' serialization form can be shared by the tzdb compiler (output
side) and the tzdb provider (input side). Given we are talking about 600+
zone (the rules number is bigger) and a total < 40k data here, I took the
simple, but slow, approach. We can revisit the start-up issue later, if 
it indeed
is a concern. Let me know if you have concern of this approach, we can go
Plan-B.

I brought back the test for the ZoneRulesBuilder, as promised. But it 
appears
there is a test failure at line#805. I have not looked into the detail 
yet. Just
wonder if you have any idea.

The changes in ZoneRulesBuilder are to workaround the
beforeOffset==afterOffset issue. The old implementation creates the trans
even two offsets are the same (use that package private constructor which
does not do sanity check), but then throw it away. The code now does the
sanity check before creating the trans.

-Sherman