315287: Handle BasicType as inheritance root of Metamodel ManagedType
http://bugs.eclipse.org/315287
https://bugs.eclipse.org/bugs/attachment.cgi?id=170738&action=diff
   The fix consists of handling inheritance trees that contain BasicTypes (a plain java class) at the root of a mixed ManagedType chain of Entity or MappedSuperclass Metamodel types.
   Currently we get an IAException during canonical metamodel generation during inheritance initialization using this type of model (predeploy is ok).

Regression tests
test-core:oracle
view e: with changes
   [junit] Tests run: 7567, Failures: 0, Errors: 11, Time elapsed: 1,443.445 sec
view f: without
   [junit] Tests run: 7567, Failures: 0, Errors: 11, Time elapsed: 1,671.552 sec

test-jpa:oracle
view f: with changes (only one ORA-00001: unique constraint db specific schema error)
    [junit] Tests run: 1976, Failures: 0, Errors: 1, Time elapsed: 1,972.449 sec
    [junit] Tests run: 98, Failures: 0, Errors: 0, Time elapsed: 43.743 sec
view f: without
    [junit] Tests run: 1965, Failures: 0, Errors: 0, Time elapsed: 1,981.498 sec
2 files changed