Bump to python 3

SConstruct

@@ -80,7 +80,7 @@ test_xml = GetOption('test_xml')
 prefix = GetOption('prefix')
 lib_suffix = ''
 if not (build_type in ['debug', 'release']):
-    print "Error: expected 'debug' or 'release', found: " + build_type
+    print("Error: expected 'debug' or 'release', found: " + build_type)
     Exit(1)
 
 def InstallPerm(env, dest, files, perm):
@@ -93,7 +93,7 @@ def InstallPerm(env, dest, files, perm):
 env = Environment(tools = ['default', 'textfile', 'packaging'])
 
 #allow shell environment to override compiler
-if os.environ.has_key('CC'):
+if os.environ.get('CC'):
     env['CC'] = os.environ['CC']
 
 env.AddMethod(InstallPerm)

include/SConscript

@@ -9,5 +9,5 @@ headers = ucore_env.Glob('ucore/*.h')
 #install targets
 
 ucore_env.Alias('install',
-    ucore_env.InstallPerm(os.path.join(prefix, 'include', 'ucore'), headers, 0644))
+    ucore_env.InstallPerm(os.path.join(prefix, 'include', 'ucore'), headers, 0o0644))