RFR [lworld] Compiler tests cleanup

[Ioi Lam]

See original discussion at 
http://mail.openjdk.java.net/pipermail/valhalla-dev/2018-July/004744.html

http://cr.openjdk.java.net/~iklam/valhalla/compiler_tests_cleanup.v01/

All of the affected compilers tests have 5 scenarios that use different
combinations of VM options. I moved the options common to all tests
to a single place, ValueTypeTest.getVMParameters(int scenario).

In the future, we can easily add more scenarios, or fine tune the 
existing ones
without going over all the tests.

Some tests add extra VM options to specific scenarios. This can be done
by overriding ValueTypeTest.getExtraVMParameters(int scenario).

The getVMParameters and getExtraVMParameters methods are generated by
a script that parses all the @run tags in the affected tests. (that's not
something that a human would be capable of doing).

I also added an property -Dscenarios=1,2 so you can pick exactly which ones
to test.

Thanks
- Ioi