openssh: drop rejected patch fixed in 8.6p1 release

openssh: drop rejected patch fixed in 8.6p1 release

The rationale [1] is that C11 6.5.6.9 says:
"""
When two pointers are subtracted, both shall point to elements of the
same array object, or one past the last element of the array object; the
result is the difference of the subscripts of the two array elements.
"""

In these cases the objects are arrays of char so the result is defined,
and we believe that the compiler incorrectly trapping on defined behaviour.

I also found https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63303
("Pointer subtraction is broken when using -fsanitize=undefined") which seems to support this position.

[1] https://bugzilla.mindrot.org/show_bug.cgi?id=2608

Signed-off-by: Jose Quaresma <jose.quaresma@foundries.io>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>