Make DynamicLibrary use ManagedStatic. This is pretty simple and should just work as

Make DynamicLibrary use ManagedStatic. This is pretty simple and should just work as
advertised - but it does have the caveat that calls to DynamicLibrary::AddSymbol will
"reset" if you shutdown llvm and try to come back for seconds.  This is a subtle
behavior change, but I'm assuming that nobody is affected by it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190921 91177308-0d34-0410-b5e6-96231b3b80d8