swift234

Re-apply "Use the 'self consumed' analysis to diagnose some invalid usages of self"

The problem was an uninitialized memory access. Callers were passing
the address of a local variable to isInitializedAtUse(), but this
function only stored to the pointer conditionally. Serendipitously
(or not), in the debug build the initial value was always zero.

Swift SVN r32599