This handles the degenerate case where SCCP replaced the value in
the RETURN opcode with a constant, but the VERIFY_RETURN is still
there. We can still apply the same optimization, just don't need
to adjust the use list in this case.

The result is still sub-optimal in that a dead QM_ASSIGN is left
behind.

Even if we don't know the exact method being called, include it
in the call graph with the is_prototype flag. In particular, we
can still make use of return types from prototype methods, as
PHP 8 makes LSP violations a hard error.

Most other places are adjusted to skip calls with !is_prototype.
Maybe some of them would be fine, but ignoring them is conservative.

Even if an explicit return type is given, we might still infer
a more narrow one based on return statements. We shouldn't
pessimize this just because a type has been declared.

And fix a type in the fetch class flags dumping while here.

* PHP-8.0:
  Fixed bug #80861 (erronous array key overflow in 2D array with JIT)

* PHP-8.0:
  Fixed bug #80839 (PHP problem with JIT)

* PHP-8.0:
  Fixed bug #80802: (zend_jit_fetch_indirect_var assert failure with tracing JIT)