init: python3.

I've actually left the two other scripts on python2, since they're not
used in the build, and I don't actually know whether anyone's still
using them manually. Leaving them on python2 should be a sign to future
maintainers (assuming they're far enough in the future) that maybe
no-one's using them and they can just be deleted instead.

Test: treehugger
Change-Id: I4d7dfdbf9f2a34ddd15cd4be077eeef2248cc596
diff --git a/init/host_builtin_map.py b/init/host_builtin_map.py
index 6afcb17..41c86ac 100755
--- a/init/host_builtin_map.py
+++ b/init/host_builtin_map.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """Generates the builtins map to be used by host_init_verifier.
 
 It copies the builtin function map from builtins.cpp, then replaces do_xxx() functions with the
@@ -39,8 +39,7 @@
   match = DO_REGEX.match(line)
   if match:
     if match.group(1) in check_functions:
-      print line.replace('do_', 'check_'),
+      line = line.replace('do_', 'check_')
     else:
-      print FUNCTION_REGEX.sub('check_stub', line),
-  else:
-    print line,
+      line = FUNCTION_REGEX.sub('check_stub', line)
+  print(line, end=' ')