RFR: JDK-8210283: Support git as an SCM alternative in the build

[Magnus Ihse Bursie]

Looks good to me. 

/Magnus

> 5 sep. 2018 kl. 18:51 skrev Erik Joelsson <erik.joelsson at oracle.com>:
> 
> It was pointed out offline that I had missed some "Mercurial" in log messages. This webrev also reintroduces the .gitignore file that was mistakenly omitted in the last webrev.
> 
> http://cr.openjdk.java.net/~erikj/8210283/webrev.03/
> 
> /Erik
> 
> 
>> On 2018-09-04 16:27, Erik Joelsson wrote:
>> New webrev: http://cr.openjdk.java.net/~erikj/8210283/webrev.02/
>> 
>> Fixed the comment in SourceRevision.gmk.
>> 
>> Added an SCM identifier in the string so a typical .src-rev file now looks like this:
>> 
>> .:hg:3f189f451ff1+
>> 
>> or like this:
>> 
>> .:git:2e1f2c6d44e5+
>> 
>> /Erik
>> 
>> 
>>> On 2018-09-04 15:00, Erik Joelsson wrote:
>>> There are several instances of OpenJDK source being hosted in Git repositories instead of Mercurial. AdoptOpenJDK is one and some engineers use local conversions for their day to day work. Project Skara aims to investigate Git as well. To better support this, the build needs to be able to support Git as an alternative to Mercurial when creating the identification hash in the release file. It would also be convenient with a .gitignore file mirroring the .hgignore file.
>>> 
>>> This patch adds such support as well as a .gitignore file.
>>> 
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8210283
>>> 
>>> Webrev: http://cr.openjdk.java.net/~erikj/8210283/webrev.01/index.html
>>> 
>>> /Erik
>>> 
>> 
>