Change ModuleEntry to struct
Change ModuleEntry to struct

Change an internal dictionary to use structs instead of classes to
reduce the amount of objects we construct.

jazzdelightsme/clrmd,JeffCyr/clrmd,stefangossner/clrmd,cshung/clrmd,Microsoft/clrmd,Microsoft/clrmd,tomasr/clrmd,stjeong/clrmd,cshung/clrmd