swift234

special case a diagnostic to produce a more sensible message when using
Builtin.addressof on an uninitialized variable.   Before:

t.swift:12:26: error: variable 'self.z' captured by a closure before being initialized
    p = UnsafePointer<Y>(Builtin.addressof(&z))
                         ^

After:

t.swift:12:26: error: address of variable 'self.z' taken before it is initialized
    p = UnsafePointer<Y>(Builtin.addressof(&z))
                         ^

This resolves rdar://15699057.



Swift SVN r11482