sanity: non utf-8 characters are tolerated

Sanity check script was not handling non utf-8 characters as a result
it crashed and didn't kill qemu and test used to hang.

Now tests fail upon untranslatable bytes.

JIRA: ZEP-673

Change-Id: I885a185e0481083501fce15cd51412bfdd26a7d7
Signed-off-by: Genaro Saucedo Tejada <genaro.saucedo.tejada@intel.com>

scripts/sanitycheck

@@ -284,7 +284,13 @@ class QEMUHandler:
                 out_state = "timeout"
                 break
 
-            c = in_fp.read(1).decode("utf-8")
+            try:
+                c = in_fp.read(1).decode("utf-8")
+            except UnicodeDecodeError:
+                # Test is writing something weird, fail
+                out_state = "unexpected byte"
+                break
+
             if c == "":
                 # EOF, this shouldn't happen unless QEMU crashes
                 out_state = "unexpected eof"