Remove floating point killer pass. This is now implemented in the

Remove floating point killer pass. This is now implemented in the
instruction selector by adding a new pseudo-instruction
FP_REG_KILL. This instruction implicitly defines all x86 fp registers
and is a terminator so that passes which add machine code at the end
of basic blocks (like phi elimination) do not add instructions between
it and the branch or return instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10562 91177308-0d34-0410-b5e6-96231b3b80d8