Track the exception pointer

[arthaud]

IKOS does not currently track the exception pointer, which leads to imprecision.

For instance, on the following code:

#include <ikos/analyzer/intrinsic.h>

void f() {
  if (__ikos_nondet_int()) {
    throw 0x42;
  }
}

int main() {
  try {
    f();
  } catch (double) {
    __ikos_assert(0);
  } catch (int) {
    __ikos_assert(1);
  }
  return 0;
}

IKOS reports:

test.cpp:13:5: error: assertion never holds
    __ikos_assert(0);
    ^

It should report this as dead code instead of reporting an error.