semihosting: fix non-zero value on Windows isatty()
On Windows, isatty() can return any non-zero value if it's an interactive
device. Which diverges from the ARM semihosting specification. This patch
introduces a fix to make the SYS_ISTTY operation conform to spec.
Change-Id: I9bc4f3cb82370812825d52419851910b3e3f35cc
Signed-off-by: Marek Vrbka <marek.vrbka@codasip.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7725
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins
Reviewed-by: Jan Matyas <jan.matyas@codasip.com>