Fix exp.volatiles_are_top and exp.globs_are_top being ignored by relational (Apron) analysis

[Copilot]

exp.volatiles_are_top (volatile/extern vars → top) and exp.globs_are_top (all globals → top) were only enforced in the base analysis (base.ml, basePriv.ml). The relational (Apron-based) analysis silently ignored these options, potentially producing unsound results when reading from volatile or extern globals.

Changes

• src/analyses/apron/relationAnalysis.apron.ml: Extended read_global to check both options after copying a global's value into a local temporary. If the global should be top, RD.forget_vars is called on the local, making it unconstrained in the relational domain. This applies to both single-threaded and multi-threaded (privatization) paths.

extern int ext;
volatile int vol;

int main(void) {
  ext = 5;
  int x = ext;        // x must be top — ext is extern
  __goblint_check(x == 5); // UNKNOWN! (was incorrectly provable before fix)

  vol = 3;
  int y = vol;        // y must be top — vol is volatile
  __goblint_check(y == 3); // UNKNOWN! (was incorrectly provable before fix)
}

• tests/regression/36-apron/100-volatiles-are-top.c: Regression test verifying the Apron interval analysis correctly treats volatile/extern globals as top when exp.volatiles_are_top is enabled.

Note: GobConfig.get_bool is already memoized via BatCache, so the per-call overhead is a single hashtable lookup — consistent with how these options are checked elsewhere in the codebase.