make sincos take type from intrinsic formal, not from result assignment

[Martin Liška]

Hello Alexander.

It seems the patch caused quite some clang warnings:

/home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-clang/build/gcc/builtins.c:2366:5: warning: comparison of different enumeration types in switch statement ('combined_fn' and 'built_in_function') [-Wenum-compare-switch]
...

Can we please fix them?
Thanks,
Martin