Rework r218304, "ExecutionEngineTests: Call llvm_shutdown() on exit for ManagedStatic introduced in r218151."

r218304 caused crash on msvc builder.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218308 91177308-0d34-0410-b5e6-96231b3b80d8