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

@@ -1,20 +1,21 @@
 #!/usr/bin/env bash
 set -eu
 . common
-after=''
+set -- ${cli_rungdb:-} "$@"
+after=
 arch='x86_64'
-before=''
+before=
 gem5=false
 lx_symbols="-ex 'lx-symbols ../kernel_module-1.0/'"
 kgdb=false
 while getopts A:a:b:gkL OPT; do
   case "$OPT" in
-    a)
-      arch="$OPTARG"
-      ;;
     A)
       after="$OPTARG"
       ;;
+    a)
+      arch="$OPTARG"
+      ;;
     b)
       before="$OPTARG"
       ;;
@@ -25,7 +26,10 @@ while getopts A:a:b:gkL OPT; do
       kgdb=true
       ;;
     L)
-      lx_symbols=''
+      lx_symbols=
+      ;;
+    ?)
+      exit 2
       ;;
   esac
 done
@@ -34,7 +38,7 @@ if [ "$#" -gt 0 ]; then
   brk="-ex 'break ${1}'"
   shift
 else
-  brk=''
+  brk=
 fi
 if "$gem5"; then
   port=7000