Fix sakura termcmd setup

Sakura `-e` is xterm compatible, so would require a `sh -c`, but it
also provides `-x` which takes a single argument, switch to that.

rc/base/x11.kak

@@ -10,7 +10,7 @@ A shell command is appended to the one set in this option at runtime} \
                    'xterm          -e sh -c' \
                    'roxterm        -e sh -c' \
                    'mintty         -e sh -c' \
-                   'sakura         -e      ' \
+                   'sakura         -x      ' \
                    'gnome-terminal -e      ' \
                    'xfce4-terminal -e      ' ; do
         terminal=${termcmd%% *}