Implement a couple of new (important) features.

1. If an operation has to be int or fp and the target only supports one
   int or fp type, relize that the op has to have that type.
2. If a target has operations on multiple types, do not emit matching code
   for patterns involving those operators, since we do not emit the code to
   check for them yet.  This prevents PPC from generating FP ops currently.

Also move some code around into more logical places.

llvm-svn: 23724