Summary: @public
This removes the old way of finding variable declarations to create sil variables and replaces it with
a a new way based on the map from pointers to declarations.
Basically, every variable dereference contains a pointer to the variable declaration, with that we can
build the corresponding sil variable.
Reviewed By: @akotulski
Differential Revision: D2536000
fb-gh-sync-id: dd29cf9
Cristiano Calcagno
Sam Blackshear
Andrzej Kotulski
Dulma Rodriguez