Fix two issues found when running Roslyn.
Fix two issues found when running Roslyn.

`loadAtAddress` of a struct type was always passing true for `IsField` when it is also used for array accesses. This caused failures for arrays of structs. Fix is to look at the ResolvedToken to determine whether the access is a field or not.

`conditionalDerefAddress` had a bug introduced when I refactored it. Since the method that hits this fails later in the reader the IR validation error hasn't yet surfaced. But Roslyn has methods where this bug causes validation errors.

manu-silicon/llilc,BruceForstall/llilc,marksantos/llilc,dkorolev/llilc,erozenfeld/llilc,AndyAyersMS/llilc,tempbottle/llilc,mmitche/llilc,pgavlin/llilc,libengu/llilc,dkorolev/llilc,libengu/llilc,marksantos/llilc,JosephTremoulet/llilc,russellhadley/llilc-original,dotnet/llilc,kyulee1/llilcjit,kyulee1/llilcjit,richardlford/llilc,mmitche/llilc,tempbottle/llilc,libengu/llilc,russellhadley/llilc,libengu/llilc,richardlford/llilc,dotnet/llilc,JosephTremoulet/llilc,manu-silicon/llilc,BruceForstall/llilc,adiaaida/llilc,swaroop-sridhar/llilc,AndyAyersMS/llilc,JosephTremoulet/llilc,swaroop-sridhar/llilc,mmitche/llilc,russellhadley/llilc-original,marksantos/llilc,erozenfeld/llilc,kyulee1/llilcjit,russellhadley/llilc-original,erozenfeld/llilc,dotnet/llilc,erozenfeld/llilc,BruceForstall/llilc,tempbottle/llilc,adiaaida/llilc,swaroop-sridhar/llilc,pgavlin/llilc,russellhadley/llilc,dkorolev/llilc,russellhadley/llilc,pgavlin/llilc,richardlford/llilc,mmitche/llilc,adiaaida/llilc,AndyAyersMS/llilc,manu-silicon/llilc,russellhadley/llilc-original