Fix installation issue on gnome-terminal 3.22 or later

[sudotac]

This PR will fix installation issue on gnome-terminal 3.22 or later.

Current behavior:
Installation failed.
The same issue as aruhier/gnome-terminal-colors-solarized#63 occurred.

$ LANGUAGE=en_US.UTF-8 gnome-terminal --version
# GNOME Terminal 3.42.2 using VTE 0.66.2 +BIDI +GNUTLS +ICU +SYSTEMD
$ LANGUAGE=en_US.UTF-8 ./terminals/gnome-terminal/install.sh

Warning!
This will permanently overwrite colors in selected profile - there is no undo.
Consider creating a new profile before installing Selenized.

Please select Selenized variant:
1) selenized-black
2) selenized-dark
3) selenized-light
4) selenized-white
#? 1

Please select a Gnome Terminal profile:

You have selected:

  Scheme:  Selenized selenized-black
Failed to get value for `/apps/gnome-terminal/profiles//visible_name': Bad key or directory name: "/apps/gnome-terminal/profiles//visible_name": Can't have two slashes '/' in a row
  Profile: (No name) ()

Are you sure you want to overwrite the selected profile?
(YES to continue) ^C

After applying this patch:
Installation succeeded.

$ LANGUAGE=en_US.UTF-8 ./terminals/gnome-terminal/install.sh

Warning!
This will permanently overwrite colors in selected profile - there is no undo.
Consider creating a new profile before installing Selenized.

Please select Selenized variant:
1) selenized-black
2) selenized-dark
3) selenized-light
4) selenized-white
#? 1

Please select a Gnome Terminal profile:
1) default
2) selenized black
#? 2

You have selected:

  Scheme:  Selenized selenized-black
  Profile: selenized black (:dc9d2c2c-02a9-48b9-aefc-5e86f2270e02)

Are you sure you want to overwrite the selected profile?
(YES to continue) YES
Confirmation received -- applying settings

Note that this patch comes from upstream (aruhier/gnome-terminal-colors-solarized@0d74f5a).
I am not the original author of this patch, and I just cherry-picked that commit.

The upstream repository is served under MIT license, and copyright notice and permission notice are already in this repository at terminals/gnome-terminal/LICENSE.mkd, so I think there is no problem.

[sudotac]

I linked to the unrelated issue by mistake, so I edited the commit message.