[OpenMP][Archer] Use dlsym rather than weak symbols for TSan annotations

This patch fix issues reported for Ubuntu and possibly other platforms:
https://github.com/llvm/llvm-project/issues/45290

The latest comment on this issue points out that using dlsym rather than
the weak symbol approach to call TSan annotation functions fixes the issue
for Ubuntu.

Differential Revision: https://reviews.llvm.org/D142378