west: bossac: handle stty on macOS better

There might be situations where people are running the coreutils version
of stty on macOS, hence the need for being smarter at detecting when
that might be the case

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

scripts/west_commands/runners/bossac.py

@@ -149,12 +149,19 @@ def get_image_offset(self, supports_offset):
 
         return None
 
+    def is_gnu_coreutils_stty():
+        try:
+            result = subprocess.run(['stty', '--version'], capture_output=True, text=True, check=True)
+            return 'coreutils' in result.stdout
+        except subprocess.CalledProcessError:
+            return False
+
     def set_serial_config(self):
         if platform.system() == 'Linux' or platform.system() == 'Darwin':
             self.require('stty')
 
             # GNU coreutils uses a capital F flag for 'file'
-            flag = '-F' if platform.system() == 'Linux' else '-f'
+            flag = '-F' if is_gnu_coreutils_stty() else '-f'
 
             if self.is_extended_samba_protocol():
                 self.speed = '1200'