patch 9.0.2129: [security]: use-after-free in call_dfunc()

patch 9.0.2129: [security]: use-after-free in call_dfunc()

Problem:  [security]: use-after-free in call_dfunc()
Solution: Refresh dfunc pointer

closes: #13571

This Commit fixes a SEGV caused by a use-after-free bug in call_dfunc().
When calling check_ufunc_arg_types() from the call_dfunc() it may cause
def functions to be re-compiled and if there are too many def functions,
the def_functions array will be re-allocated.  Which means, that the
dfunc pointer in call_dfunc() now starts pointing to freed memory.

So we need to reset the dfunc pointer after calling
check_ufunc_arg_types().

Let's also add a test, to ensure we do not regress.

Signed-off-by: mityu <mityu.mail@gmail.com>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>