[OpenMP] libomp: fix build by clang-cl with vs2019

Problem reported by Joseph Shen <joseph.smeng@gmail.com>.
The patch changes *(&<atomic-var>) to (&<atomic-var>)->load().

Differential Revision: https://reviews.llvm.org/D95485

GitOrigin-RevId: 498c4b6fc45ae4704a7f93bd03e018392bb87945
1 file changed