Fix incremental invariant parser for server mode

[sim642]

This hopefully fixes the following issue.

Issue

// repro.c
int global = 32;

int main() {
    int local = 3;
}

// goblint.json
{
  "files": ["repro.c"]
}

After reanalysis arg/eval-int will return top for the expression global.

Note: running analysis with reset=false you need to analyze, comment out global, reanalyze, comment in global and reanalyze again to get the issue to happen. Running analysis with reset=true you just need to analyze twice.

Originally posted by @FeldrinH in #1008 (comment)

[FeldrinH]

The issue appears to be fixed. Everything looks good to me.