RFR[M]: Adding MD5 Intrinsic on x86-64

[Ludovic Henry]

Webrev: http://cr.openjdk.java.net/~luhenry/8250902/webrev.03
Testing: everything passes with hotspot:tier1 and jdk:tier1 in fastdebug on Linux-x64.

> I would leave this investigation to Intel's Java group. They are expert in this area!

Ok, we'll reach out to Intel on our end as well to figure out whether they have any specific guidance on that.

> 3. Just add MD5 tests into existing SHA directory.

Done. I've done some small renames (TestSHA -> TestDigest, SHAOptionsBase -> DigestOptionsBase), modified some of the SHA-specific code for non-SHA cases (GenericTestCaseFor*.java), and added MD5-specific tests.

> Note, compiler/intrinsics/sha testing is done in tier2. I ran it and it passed but it does not test MD5 a lot as I understand.

I extended the existing tests to cover MD5 on the same level as SHA, and I made sure that all tests are still passing.

>> 
>>> In vm_version_x86.cpp move UseMD5Intrinsics flag setting near UseSHA flag setting.
>> 
>> Fixed.
>
> It is not moved in webrev.02

Fixed.

> You don't need to use Oracle copyright line. Using original Microsoft's copyright line is fine since you are author.

Fixed.