Change all C code to return ndn_Error enum instead of char * error string.
diff --git a/Makefile.am b/Makefile.am
index 6717439..0ddbb32 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -17,6 +17,7 @@
   config.h \
   ndn-cpp/c/Interest.h \
   ndn-cpp/c/Name.h \
+  ndn-cpp/c/errors.c ndn-cpp/c/errors.h \
   ndn-cpp/c/encoding/BinaryXML.h \
   ndn-cpp/c/encoding/BinaryXMLDecoder.c ndn-cpp/c/encoding/BinaryXMLDecoder.h \
   ndn-cpp/c/encoding/BinaryXMLEncoder.c ndn-cpp/c/encoding/BinaryXMLEncoder.h \