[LowerEmuTls] Copy dso_local from <var> to __emutls_v.<var>

This effect is not testable until we drop the implied dso_local for ELF
static/PIE defined symbols from TargetMachine::shouldAssumeDSOLocal.

llvm/lib/CodeGen/LowerEmuTLS.cpp

@@ -44,6 +44,7 @@ private:
                                     GlobalVariable *to) {
     to->setLinkage(from->getLinkage());
     to->setVisibility(from->getVisibility());
+    to->setDSOLocal(from->isDSOLocal());
     if (from->hasComdat()) {
       to->setComdat(M.getOrInsertComdat(to->getName()));
       to->getComdat()->setSelectionKind(from->getComdat()->getSelectionKind());