[OpenMP][bugfix] Add missing math functions variants for log and abs.

[OpenMP][bugfix] Add missing math functions variants for log and abs.

Summary: When including the random header in C++, some of the math functions it relies on are not present in the CUDA headers. We include this variants in this case.

Reviewers: jdoerfert, hfinkel, tra, caomhin

Reviewed By: tra

Subscribers: efriedma, guansong, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62046

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@361066 91177308-0d34-0410-b5e6-96231b3b80d8