[Alignment][NFC] Transition and simplify calls to DL::getABITypeAlignment

This patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Differential Revision: https://reviews.llvm.org/D82956

llvm/lib/IR/DataLayout.cpp

@@ -52,7 +52,7 @@ StructLayout::StructLayout(StructType *ST, const DataLayout &DL) {
   // Loop over each of the elements, placing them in memory.
   for (unsigned i = 0, e = NumElements; i != e; ++i) {
     Type *Ty = ST->getElementType(i);
-    const Align TyAlign(ST->isPacked() ? 1 : DL.getABITypeAlignment(Ty));
+    const Align TyAlign = ST->isPacked() ? Align(1) : DL.getABITypeAlign(Ty);
 
     // Add padding if necessary to align the data element properly.
     if (!isAligned(TyAlign, StructSize)) {