swift234

Use signed char for 32-bit Watch Simulator

For integral types, the WatchKit remote procedure call mechanisms only
consider signed numbers (rdar://problem/21153645) and the boolean
type. We were incorrectly assuming that all bools are i1, even on
platforms where bool maps to signed char, such as armv7k, arm64, and
iOS x86_64.

Mark Objective-C type encoded strings that bool -> signed char
when Clang says so.

Fixes: rdar://problem/21129609
See Also: rdar://problem/21131808

Swift SVN r29141