scripts/runqemu: Add always ttyS1 when no serial options are specified

We always wants ttyS0 and ttyS1 in qemu machines (see SERIAL_CONSOLES),
if not serial or serialtcp options was specified only ttyS0 is created
and sysvinit shows an error trying to enable ttyS1:

     INIT: Id "S1" respawning too fast: disabled for 5 minutes

[YOCTO #10491]

(From OE-Core rev: 3a0efbbe6bb5a7f0fb3df0f6052b11e56788405f)

(From OE-Core rev: ab8d1a73ad5285dbc86352813b24db2adb3c6367)

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu

@@ -1078,6 +1078,17 @@ class BaseConfig(object):
             elif serial_num == 1:
                 self.qemu_opt += " %s" % self.get("QB_SERIAL_OPT")
 
+        # We always wants ttyS0 and ttyS1 in qemu machines (see SERIAL_CONSOLES),
+        # if not serial or serialtcp options was specified only ttyS0 is created
+        # and sysvinit shows an error trying to enable ttyS1:
+        #     INIT: Id "S1" respawning too fast: disabled for 5 minutes
+        serial_num = len(re.findall("-serial", self.qemu_opt))
+        if serial_num == 0:
+            if re.search("-nographic", self.qemu_opt):
+                self.qemu_opt += " -serial mon:stdio -serial null"
+            else:
+                self.qemu_opt += " -serial mon:vc -serial null"
+
     def start_qemu(self):
         if self.kernel:
             kernel_opts = "-kernel %s -append '%s %s %s'" % (self.kernel, self.kernel_cmdline, self.kernel_cmdline_script, self.get('QB_KERNEL_CMDLINE_APPEND'))