Revert "Remove unnecessary singleton record from CompareAST.global_identifier"
Revert "Remove unnecessary singleton record from CompareAST.global_identifier"

This reverts commit 8692ebf1099f7100730f5f73f0e5f2116dcf6fa1.

goblint/analyzer,goblint/analyzer,goblint/analyzer,goblint/analyzer,goblint/analyzer