RFR: JDK-8001191: use -source 8 -target 8 when compiling the JDK

[Kumar Srinivasan]

Hello,

Please review changes to rev up the default -source and -target for jdk 
compilation,
thus producing v52.0 class files.

Bug is here:
https://jbs.oracle.com/bugs/browse/JDK-8001191

Webrev is here:
http://cr.openjdk.java.net/~ksrini/8001191/webrev.0/

Note: this webrev is generated against the master repository but changes 
will be
pushed via tl  after the tl-master sync is completed.

Thanks
Kumar