LoopInvariantCodeMotion: don't hoist `load [take]`
Usually `load [take]` is not hoisted anyway, because there must be another instruction in the loop which re-initializes the loaded memory location.
However, this is not necessarily true for alloc_stack locations with dynamic lifetime, e.g. a pack-loop which is specialized for a single pack element (at runtime the loop is only executed once).
Fixes a SIL ownership verifier crash
rdar://167504916
