llvmdg: fix building subgraphs from casted func calls
llvmdg: fix building subgraphs from casted func calls

We need to strip the casts from the function to find out
what's inside

Signed-off-by: Marek Chalupa <a05df156a69ad59faa9af9b666ef78009594c145@gmail.com>

mchalupa/dg,mchalupa/dg,mchalupa/dg,mchalupa/dg