Reapply "[msan] Add avx512-intrinsics.ll and avx512-intrinsics-upgrade.ll test case (#123980)"

This reverts commit b2647ff i.e.,
relands
980e86f.

I had reverted it because of buildbot failures (e.g., https://lab.llvm.org/buildbot/#/builders/13/builds/4938/steps/5/logs/FAIL__LLVM__avx512-intrinsics-upgrade_ll), which I misdiagnosed. The likely root cause is that the target datalayout had not been specified; this reland adds that.

Author: thurstond