configs: common: Add tmux support for ncurses

This commit updates the common toolchain configurations to explicitly
set the list of supported terminal types for the ncurses library and
adds `screen`, `screen-256color`, `tmux`, `tmux-256color` terminal type
support.

These terminal types are required in order to properly handle user
inputs (e.g. for GDB shell) inside tmux.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

Author: stephanosio

configs/common.config

@@ -1,5 +1,8 @@
 # Common crosstool-ng configurations for all toolchain variants
 
+# Ncurses
+CT_NCURSES_HOST_FALLBACKS="linux,xterm,xterm-color,xterm-256color,vt100,screen,screen-256color,tmux,tmux-256color"
+
 # Binutils
 CT_BINUTILS_SRC_CUSTOM=y
 CT_BINUTILS_CUSTOM_LOCATION="${GITHUB_WORKSPACE}/binutils"