Not pushing conditions using permission introspection further in

[marcoeilers]

The --conditionalizePermissions command line option rewrites implications and ternary expressions to avoid branching.
The general pattern is that e1 ==> acc(e2.f, e3) is rewritten to acc(e2.f, e1 ? e3 : none.

This rewriting is not always sound if the condition (e1 in this case) uses permission introspection.
Example:

inhale P1(x)
exhale perm(P1(x)) >= write ==> (P1(x) && P1(x))

must not be rewritten to

inhale P1(x)
exhale acc(P1(x), perm(P1(x)) >= write ? write : none) && acc(P1(x), perm(P1(x)) >= write ? write : none)

since the value of perm(P1(x)) >= write changes.

This PR conservatively prevents any rewriting where the condition contains perm or forperm.
This fixes one issue mentioned in #851.

[jcp19]

The code looks ok to me, I have a few questions about the tests though