tools: from io import StringIO in ninja.py

Author: cclauss

tools/gyp/pylib/gyp/generator/ninja.py

@@ -20,7 +20,7 @@
 import gyp.msvs_emulation
 import gyp.MSVSUtil as MSVSUtil
 import gyp.xcode_emulation
-from cStringIO import StringIO
+from io import StringIO
 
 from gyp.common import GetEnvironFallback
 import gyp.ninja_syntax as ninja_syntax