Exits successfully with :cq

[bk2204]

Describe the bug
When invoked as nvim-gtk --no-fork, running the :cq command exits successfully.

The documentation for :cq specifies that it's supposed to cause Neovim to exit with an error code, either the one specified, or a generic one. This is important to abort git commit and other similar programs when an editor has been spawned.

Description of what the bug is.

Technical information (please complete the following information):

• OS: Debian amd64/sid (unstable)
• Neovim version: 0.4.4
• Neovim-Gtk build version: The revision at Listen to VimResized event and resize the window when needed #264.