RFR(L): More migration to the L-world

[Frederic Parain]

Please review the following patch:

http://cr.openjdk.java.net/~fparain/field_flattening/webrev.00/index.html

This patch was started as a fix for field flattening but it ended
being an omnibus patch addressing the following issues:
   - Fixed value types runtime tests accordingly to the new language
     support in javac
   - Fixed storage and propagation of the ACC_FLATTENABLE flag in JVM
     meta-data
   - Fixed value flattening for value fields with the ACC_FLATTENABLE
     flag set
   - Fixed uninitialized value for fields with ACC_FLATTENABLE flag set
   - Fixed klass initialization sequence for ACC_FLATTENABLE support
   - Implemented flattenable semantic for value fields with
     ACC_FLATTENABLE flag set
   - Added test to verify flattenable semantic
   - Fixed a bug in the verifier (withfield)


With this patch, most tests in the runtime/valhalla/valuetypes
directory now pass in interpreted mode. Only 3 tests still fail,
2 because of the value array code that has not been migrated to
the L-world, 1 because of the Bytecode API which has not been
migrated either.

Builds and tests (TEST=hotspot_valhalla_runtime) have been run on
Linux/X64 and MacOSX/X64.

Thank you,

Fred