[WPD] Directly create geteleementptr inbounds (NFCI)

We know that this GEP is inbounds, so make it explicit. NFCI
because constant expression construction already infers this.

Author: nikic

llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp

@@ -1927,7 +1927,7 @@ void DevirtModule::rebuildGlobal(VTableBits &B) {
   // element (the original initializer).
   auto Alias = GlobalAlias::create(
       B.GV->getInitializer()->getType(), 0, B.GV->getLinkage(), "",
-      ConstantExpr::getGetElementPtr(
+      ConstantExpr::getInBoundsGetElementPtr(
           NewInit->getType(), NewGV,
           ArrayRef<Constant *>{ConstantInt::get(Int32Ty, 0),
                                ConstantInt::get(Int32Ty, 1)}),