make: In include/Makefile.am, use $(wildcard) so that we only list directories.
diff --git a/Makefile.am b/Makefile.am
index 75cc28b..0271ead 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -18,6 +18,7 @@
bin/test-get-async bin/test-publish-async
# Public C headers.
+# NOTE: If a new directory is added, then add it to ndn_cpp_c_headers in include/Makefile.am.
ndn_cpp_c_headers = \
include/ndn-cpp/ndn-cpp-config.h \
include/ndn-cpp/c/common.h \
@@ -28,6 +29,7 @@
include/ndn-cpp/c/encoding/element-listener.h
# Public C++ headers.
+# NOTE: If a new directory is added, then add it to ndn_cpp_cpp_headers in include/Makefile.am.
ndn_cpp_cpp_headers = \
include/ndn-cpp/common.hpp \
include/ndn-cpp/data.hpp \