gnuplot: remove obviated patch

Since glib 2.36 the patch is unnecessary.

Closes #18900.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
icalbuddy 1.8.8

Closes #18902.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
cppcheck 1.59

Closes #18897.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
httping 2.1

Closes #18898.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>