Create the cli.gitignore mechanism to pass extra default cli options

Document that X11 mouse is not moving.

Convert x='' to x= on all scripts, and also fix case ;; indentations.

Add dummy value to QEMU's -trace enable= to prevent warning.

Expand built-in package choice rationale.

rungdb-user

@@ -1,10 +1,11 @@
 #!/usr/bin/env bash
 set -eu
 . common
+set -- ${cli_rungdb_user:-} "$@"
 usage="$0 <exec-relative-path> [<brk-symbol>]"
 arch='x86_64'
 gem5=false
-gem5_opt=''
+gem5_opt=
 while getopts a:gh OPT; do
   case "$OPT" in
     a)
@@ -18,6 +19,9 @@ while getopts a:gh OPT; do
       echo "$usage"
       exit 0
       ;;
+    ?)
+      exit 2
+      ;;
   esac
 done
 shift "$(($OPTIND - 1))"
@@ -27,7 +31,7 @@ if [ "$#" -gt 0 ]; then
   brk="'$1'"
   shift
 else
-  brk=''
+  brk=
 fi
 set_common_vars "$arch" "$gem5"
 executable="${build_dir}/${executable_rel}"