swift234

SIL: Use SILType and lower types where needed.
Change over SIL Values and Instructions to work in terms of SILTypes, and update SILGen to lower types where needed. Add LValueType logic to SILType lowering to get rid of those annoying lvalue qualifiers so we can ignore RequalifyExprs. Tighten up the XFAILs in the SIL tests and disable the checks that currently crash.

Swift SVN r3538