clint: use fileinput for stdin

Fixes handing of "-" on Python 3:

    Traceback (most recent call last):
      File "…/Vcs/neovim/src/clint.py", line 3625, in <module>
        main()
      File "…/Vcs/neovim/src/clint.py", line 3618, in main
        ProcessFile(filename, _cpplint_state.verbose_level)
      File "…/Vcs/neovim/src/clint.py", line 3464, in ProcessFile
        'replace').read().split('\n')
      File "/usr/lib/python3.7/codecs.py", line 701, in read
        return self.reader.read(size)
      File "/usr/lib/python3.7/codecs.py", line 500, in read
        data = self.bytebuffer + newdata
    TypeError: can't concat str to bytes

1 files changed, 5 insertions, 4 deletions

diff --git a/src/clint.py b/src/clint.py
index 9fd93ce143..cb08b52dc6 100755
--- a/src/clint.py
+++ b/src/clint.py
@@ -49,6 +49,7 @@ from __future__ import unicode_literals
 
 import codecs
 import copy
+import fileinput
 import getopt
 import math  # for log
 import os
@@ -3456,10 +3457,10 @@ def ProcessFile(filename, vlevel, extra_check_functions=[]):
         # is processed.
 
         if filename == '-':
-            lines = codecs.StreamReaderWriter(sys.stdin,
-                                              codecs.getreader('utf8'),
-                                              codecs.getwriter('utf8'),
-                                              'replace').read().split('\n')
+            stdin = sys.stdin.read()
+            if sys.version_info < (3, 0):
+                stdin = stdin.decode('utf8')
+            lines = stdin.split('\n')
         else:
             lines = codecs.open(
                 filename, 'r', 'utf8', 'replace').read().split('\n')