[OpenMP] update test cases for -std=c++11 compile

target_parallel_for_simd_collapse_messages.cpp and target_parallel_for_simd_ordered_messages.cpp give different diagnostic messages in compiling with -std=c++11. The test cases are updated to make it compatible.

Differential Revision: https://reviews.llvm.org/D22417

llvm-svn: 275805