Added recovery step for failed QEMU operation (#112)

On current QEMU versions, failed to exit cleanly will cause the current
session of command line unable to echo typed characters.

This change added a step to try to recover from such state, in Linux,
when QEMU returns with errors.

Platforms/QemuQ35Pkg/Plugins/QemuRunner/QemuRunner.py

@@ -119,6 +119,10 @@ def Runner(env):
         # Run QEMU
         #ret = QemuRunner.RunCmd(executable, args,  thread_target=QemuRunner.QemuCmdReader)
         ret = utility_functions.RunCmd(executable, args)
+        if ret != 0 and os.name != 'nt':
+            # Linux version of QEMU will mess with the print if its run failed, this is to restore it
+            utility_functions.RunCmd ('stty', 'echo')
+
         ## TODO: restore the customized RunCmd once unit tests with asserts are figured out
         if ret == 0xc0000005:
             ret = 0