Reapply r343129 with fix.

Explicitly defines ThreadSafeModule's move-assignment operator to move fields in
reverse order. This is required to ensure that the context field outlives the
module field.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343149 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed