Reduce abuse of default values in the GlobalAlias constructor.

This is in preparation for adding an optional offset.

llvm-svn: 209073
diff --git a/llvm/lib/Linker/LinkModules.cpp b/llvm/lib/Linker/LinkModules.cpp
index cf49d3f..518b681 100644
--- a/llvm/lib/Linker/LinkModules.cpp
+++ b/llvm/lib/Linker/LinkModules.cpp
@@ -922,9 +922,8 @@
   // If there is no linkage to be performed or we're linking from the source,
   // bring over SGA.
   auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
-  auto *NewDA =
-      new GlobalAlias(PTy->getElementType(), SGA->getLinkage(), SGA->getName(),
-                      /*aliasee*/ nullptr, DstM, PTy->getAddressSpace());
+  auto *NewDA = new GlobalAlias(PTy->getElementType(), PTy->getAddressSpace(),
+                                SGA->getLinkage(), SGA->getName(), DstM);
   copyGVAttributes(NewDA, SGA);
   if (NewVisibility)
     NewDA->setVisibility(*NewVisibility);