Do not use host floating point types when emitting

Do not use host floating point types when emitting
ASCII IR; loading and storing these can change the
bits of NaNs on some hosts.  Remove or add warnings
at a few other places using host floating point;
this is a bad thing to do in general.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62712 91177308-0d34-0410-b5e6-96231b3b80d8