signal: Add example of signal handler throwing exception.

signal/example_sigint_exc.py

@@ -0,0 +1,21 @@
+import time
+from signal import *
+
+quit = 0
+
+def handler(signum):
+    global quit
+#    quit = 1
+    print('Signal handler called with signal', signum)
+    raise OSError("Couldn't open device!")
+
+print("org signal() val:", signal(SIGINT, handler))
+print("read back signal() val:", signal(SIGINT, handler))
+
+try:
+    while not quit:
+        time.sleep(10)
+except:
+    print("Caught exc")
+
+print("Quitting")