Use a custom expander for all FP to int conversions, as the X86 only has

Use a custom expander for all FP to int conversions, as the X86 only has
FP-to-int-in-memory: this exposes the load from the stored slot to the
selection dag, allowing it to be folded into other operaions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22556 91177308-0d34-0410-b5e6-96231b3b80d8