Crash when using core models and comparing two inputs

[thk123]

Given the following Java:

class Test2Class {
  static void test(Object a, Object b) {
    assert(a == b);
  }
}

When running jbmc with the core models: jbmc Test2Class.class --function Test2Class.test --classpath ../../../src/java_bytecode/library/core-models.jar:.

The following error is generated:

struct: component type does not match: signedbv
  * width: 32
  * #c_type: signed_int vs. 
terminate called after throwing an instance of 'int'
Aborted (core dumped)

The component that is specifically the wrong type is monitorCount from java.lang.Object model.

[Degiorgio]

The following PR when merged should fix this: #2280