swift234

SIL: Lower @objc_blocks with the correct calling and ownership conventions.

Force @objc_blocks to use the @cc(cdecl) calling convention, so that calling them undergoes bridging conversions in SILGen, and give them the correct ownership conventions so that the callee, arguments, and result are passed +0. This unfortunately ruins our ability to verify bridge_to_block instructions at all, but bridge_to_block is a hack anyway, and this is a necessary prerequisite to actually being able to call blocks in IRGen.

Swift SVN r13923