make: change to AC_CONFIG_SRCDIR([configure.ac]) since we moved config.h.in.
diff --git a/configure b/configure
index df775ad..c7d181b 100755
--- a/configure
+++ b/configure
@@ -595,7 +595,7 @@
 PACKAGE_BUGREPORT='ndn-lib@lists.cs.ucla.edu'
 PACKAGE_URL='https://github.com/named-data/ndn-cpp'
 
-ac_unique_file="config.h.in"
+ac_unique_file="configure.ac"
 # Factoring default headers for most tests.
 ac_includes_default="\
 #include <stdio.h>
diff --git a/configure.ac b/configure.ac
index 8e35d3f..ec2f280 100644
--- a/configure.ac
+++ b/configure.ac
@@ -15,7 +15,7 @@
 AM_INIT_AUTOMAKE([1.10 -Wall no-define foreign])
 
 AC_CONFIG_MACRO_DIR([m4])
-AC_CONFIG_SRCDIR([config.h.in])
+AC_CONFIG_SRCDIR([configure.ac])
 # Create config.h without prefixes.  Put it in the include directory so CFLAGS will have -I./include .
 AC_CONFIG_HEADERS(include/config.h)
 # Add prefixes and output to a unique file name which will go into the ndn-cpp include install directory.