Add in_c_key property to ctc.root config variable

theano/configdefaults.py

@@ -1768,7 +1768,7 @@ AddConfigVar(
     'Directory which contains the root of Baidu CTC library. It is assumed \
     that the compiled library is either inside the build, lib or lib64 \
     subdirectory, and the header inside the include directory.',
-    StrParam('', allow_override=False))
+    StrParam('', allow_override=False, in_c_key=False))
 
 # Check if there are remaining flags provided by the user through THEANO_FLAGS.
 for key in THEANO_FLAGS_DICT.keys():