[compat] Add compat_input

youtube_dl/compat.py

@@ -482,6 +482,11 @@ def compat_getpass(prompt, *args, **kwargs):
 else:
     compat_getpass = getpass.getpass
 
+try:
+    compat_input = raw_input
+except NameError:  # Python 3
+    compat_input = input
+
 # Python < 2.6.5 require kwargs to be bytes
 try:
     def _testfunc(x):