swift234

Overhaul the handling of return locations for auto-generated code.
- change SILGenFunction to use Cleanup and Implicit return locations for
  auto-generated cleanups/returns where sensible.
- Fix a bug in where ConstructorDecl that would return the wrong
  source range.
- Move the expected locations of some errors to the end of the function
  where they should belong.

Fixes <rdar://problem/15609768> Line tables for classes that don't have
init but just initialize ivars are odd

Swift SVN r11086