Expose Parcel read/writeBoolean.

Previously the recommendation seemed to be to just call read/writeInt with a ternary, but if that isn't good enough for internal callers then it isn't good enough for external ones. Plus there's tons of StackOverflow questions and "me too"s on a 8-year-old bug. Boolean is sufficiently ubiquitous as a type to warrant a public method.

Bug: 36912353
Test: none
Change-Id: I7fac76d8ea8647b09b87befbcba41f3f0f2de1dc