runqemu: Replaced "stty sane" with saved stty settings

stty manual says :

"sane - Resets all modes to reasonable values for interactive terminal use."

But reasonable isn't the most viable solution, because we want to keep the
original stty settings before running runqemu. Saving the stty settings and
setting them at the end of the runqemu script solves the terminal
settings differences after the script ran.

[Yocto #4512]

(From OE-Core rev: 93e0ae68d2c1827370f4f9e95c2f0b7f98ba2cb8)

Signed-off-by: Andrei Dinu <andrei.adrianx.dinu@intel.com>
[Added filename info in commit subject - sgw]
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu-internal

@@ -104,6 +104,9 @@ fi
 
 NFSRUNNING="false"
 
+#capture original stty values
+ORIG_STTY=$(stty -g)
+
 if [ "$SLIRP_ENABLED" = "yes" ]; then
     KERNEL_NETWORK_CMD=""
     QEMU_TAP_CMD=""
@@ -221,7 +224,11 @@ else
             fi
             # If QEMU crashes or somehow tty properties are not restored
             # after qemu exits, we need to run stty sane
-            stty sane
+            #stty sane
+
+            #instead of using stty sane we set the original stty values
+            stty ${ORIG_STTY}
+
         }
 
 
@@ -589,6 +596,8 @@ if [ "$SLIRP_ENABLED" != "yes" ]; then
         cleanup
 fi
 
+#set the original stty values before exit
+stty ${ORIG_STTY}
 trap - INT TERM QUIT
 
 return $ret