RFR 8157308: DRBG serialization fix

[Wang Weijun]

Ping again. 

> 在 2016年5月19日，16:21，Wang Weijun <weijun.wang at oracle.com> 写道：
> 
> Please take a review at
> 
>   http://cr.openjdk.java.net/~weijun/8157308/webrev.00/
> 
> Now that DRBG does not save any internal state during serialization, all DRBG implementations (HashDrbg, HmacDrbg, CtrDrbg) still extends SecureRandomSpi and contain quite some @serial fields. If some of them is corrupted a deserialized DRBG may run expectedly, it also prevents class evolution.
> 
> The fix is to make AbstractDrbg no more a SecureRandomSpi child so no more serializable. DRBG is still a SecureRandomSpi child and its only @serial field is MoreDrbgParameters mdp. MoreDrbgParamaters is also made serializable.
> 
> One new test is added. Since AbstractDrbg is no longer a SecureRandomSpi, its child class can no longer be registered in a SecureRandom provider, and the AbstractDrbgSpec.java test is removed.
> 
> Thanks
> Max
>