icd: clean up alloc functions

Clean up and move alloc functions to icd-alloc.[ch].
diff --git a/icd/intel/obj.c b/icd/intel/obj.c
index 5941f26..64d83d0 100644
--- a/icd/intel/obj.c
+++ b/icd/intel/obj.c
@@ -251,7 +251,7 @@
 
     memset(dbg, 0, dbg_size);
 
-    dbg->alloc_id = icd_get_allocator_id();
+    dbg->alloc_id = icd_allocator_get_id();
     dbg->type = type;
     dbg->dev = dev;