[CIR] Correct 'null' init for array types with non-zero init (#229543)
The member pointers are supposed to be initialized to -1, so an array of
them or a record of them needs to be initialized properly to -1. This
patch makes sure we look through array types/etc to get the correct
initialization.
Also, quite a few places were using 'getZeroAttr' when they meant 'null
init', so this changes that as well.