swift234

SILGen: Carefully preserve 'self' at +1 through init delegation.

CALayer and potentially other framework classes implement their own refcounting
schemes that assume [self retainCount] == 1 at initialization time, a guarantee
SILGen didn't attempt to meet until now. Set a flag in SILGenFunction while
doing initializer delegations to indicate that a 'self' reference can consume
the current 'self' binding, and reinitialize rather than reassign 'self' with
the result of the delegation if it was successfully consumed. Fixes
<rdar://problem/17014037>.

Swift SVN r18608