[Driver] Register effective triple before get arm float abi.

Summary:
We need to register effective triple before calling `getARMFloatABI`.
Add missing code when `--print-libgcc-file-name` is passed.

Reviewers: atanasyan, rsmith, mgorny, peter.smith, kristof.beyls, compnerd, jroelofs

Reviewed By: compnerd

Subscribers: llvm-commits, aemerson, javed.absar, srhines, kristof.beyls, pirama

Differential Revision: https://reviews.llvm.org/D35742

llvm-svn: 311624