[TargetLibraryInfo] add mappings from LLVM sin/cos intrinsics to SVML calls

These weren't included in D19544 - probably just an oversight.
D40044 made it more likely that we'll have LLVM math intrinsics rather 
than libcalls, so this bug was more easily exposed.
As the tests/code show, we already have the complete mappings for pow/exp/log.

I don't have any experience with SVML, so I don't know if anything else is 
missing. It's also not clear to me that we should be doing this transform in 
IR rather than DAG/isel, but that's a separate issue.

Differential Revision: https://reviews.llvm.org/D47610

llvm-svn: 334211