[OpenMP] offload issue with complex

[ye-luo]

I got hang

clang++ -fopenmp -fopenmp-targets=nvptx64 -Xopenmp-target=nvptx64 -march=sm_80 -O3 complex.cpp && ./a.out 

code

if I add -ffast-math, this reproducer passes

clang++ -fopenmp -fopenmp-targets=nvptx64 -Xopenmp-target=nvptx64 -march=sm_80 -O3 -ffast-math complex.cpp && ./a.out 

issue starts at the same time as #56753

[llvmbot]

@llvm/issue-subscribers-openmp

[ye-luo]

/cherry-pick a8cda32

[llvmbot]

/branch llvm/llvm-project-release-prs/issue57064

[llvmbot]

/pull-request llvm/llvm-project-release-prs#99