remove QStartupWithShell entry from NEWS::Changes in GDB 7.11

remove QStartupWithShell entry from NEWS::Changes in GDB 7.11

This entry was added twice within the same commit, back in Dec 2017
by the following change:

    commit aefd8b33d97bded58e51d75271f99e1eaec9fb28
    Date:   Thu Dec 22 22:14:02 2016 -0500
    Subject: Implement proper "startup-with-shell" support on gdbserver

I think the second entry is just a rebase/merge oversight, and it wasn't
meant to be added there, particularly since the 7.11 branch was no longer
active at that time anymore.

This patch just removes the entry.

gdb/ChangeLog:

	* NEWS (Changes in GDB 7.11): Remove entry for QStartupWithShell.