This is the new version of the patch that removes the "lto1 target 
specific builtin not available" error message happening in the LTO 
streamer-in while loading the NEON intrinsic in the global context, 
without arm_fpu_index being set with the current FPU mode.

nb: Needs https://gcc.gnu.org/ml/gcc-patches/2015-12/msg01714.html to pass

Also robustified the associated test.

Thanks,