The main idf.py process has a handler for SIGINT, which actually just
ignores it. The get_default_serial_port() function is called within the
idf.py context to detect port for several tools(monitor,flash) and it's
not possible to terminate it because of this. Let's ignore SIGINT only
while running idf_monitor, which uses it to spawn gdb.
Fixes: c6e3eb0922 ("idf.py.exe changes to handle Ctrl+C in correct way. H..")
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>