According to gdb documentation, `g` and `p` packets can report a
register being unavailable by a string of 'x' instead of register's
value.
Change-Id: I8ef279f1357c2e612f5d3290eb0022c1b47d9fa7
Signed-off-by: Evgeniy Naydanov <evgeniy.naydanov@syntacore.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7876
Reviewed-by: Marek Vrbka <marek.vrbka@codasip.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Anatoly Parshintsev <kupokupokupopo@gmail.com>
Tested-by: jenkins