Relax one assertion -- long double has strange alignments on lots of

platforms.

Also, remove one assertion on MSVC because it produces a completely
preposterous result, claiming something needs 12-byte alignment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158599 91177308-0d34-0410-b5e6-96231b3b80d8