Make -ffp-contract a codegen option, rather than a laguage option. This makes

Make -ffp-contract a codegen option, rather than a laguage option. This makes
more sense anyway - it determines how expressions are codegen'd. It also ensures
that -ffp-contract=fast has the intended effect when compiling LLVM IR.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168027 91177308-0d34-0410-b5e6-96231b3b80d8