this does is reconstruct the type for structs and arrays if the type
wouldn't be compatible otherwise.
The assertion about packing in the struct type reconstruction code
sucks, but I don't see any obvious way to fix it. Maybe we need a general
utility method to take a list of types and alignments and try to construct an
unpacked type if possible?
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@51785 91177308-0d34-0410-b5e6-96231b3b80d8