Fix issues with ldind.ref and multidimensional array get
Fix issues with ldind.ref and multidimensional array get

Closes #847.

When getting a value from a multidimensional array of reference types, the runtime creates an array get stub that does a bunch of raw pointer math feeding a `ldind.ref`. Ensure that we have reasonable typing for this case.

AndyAyersMS/llilc,marksantos/llilc,manu-silicon/llilc,swaroop-sridhar/llilc,adiaaida/llilc,JosephTremoulet/llilc,adiaaida/llilc,dotnet/llilc,JosephTremoulet/llilc,swaroop-sridhar/llilc,AndyAyersMS/llilc,russellhadley/llilc,swaroop-sridhar/llilc,kyulee1/llilcjit,adiaaida/llilc,russellhadley/llilc,BruceForstall/llilc,BruceForstall/llilc,AndyAyersMS/llilc,dotnet/llilc,marksantos/llilc,manu-silicon/llilc,manu-silicon/llilc,kyulee1/llilcjit,JosephTremoulet/llilc,BruceForstall/llilc,dotnet/llilc,marksantos/llilc,kyulee1/llilcjit,russellhadley/llilc