[OpenMP] Remove compilation warning when using clang to compile bc files.

Summary: Minor printf format correction. NVCC ignore those. Clang will give warning on these if debug is enabled.

Reviewers: grokos

Reviewed By: grokos

Subscribers: openmp-commits

Tags: #openmp

Differential Revision: https://reviews.llvm.org/D45528

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@330944 91177308-0d34-0410-b5e6-96231b3b80d8