Add json-c in config

build/ac/Makefile.am

@@ -63,7 +63,8 @@ ac_SOURCES = \
 ac_LDADD = \
 	$(CONFIG_LIBS) \
 	$(PTHREAD_LIBS) \
-	$(LIBXML2_LIBS)
+	$(LIBXML2_LIBS) \
+	$(LIBJSON_LIBS)
 
 if DTLS_ENABLED
 ac_LDADD += $(SSL_LIBS)

configure.ac

@@ -140,6 +140,21 @@ PKG_CHECK_MODULES(
 	[libxml-2.0 >= 2.6]
 )
 
+# Check JSON library
+if test "${enable_ac}" = "yes"; then
+	PKG_CHECK_MODULES(
+		[LIBJSON], 
+		[json-c >= 0.11], 
+		[], 
+		[PKG_CHECK_MODULES(
+			[LIBJSON],
+			[json >= 0.9],
+			[],
+			[AC_MSG_ERROR(You need the libjson)]
+		)]
+	)
+fi
+
 # Check nl80211
 has_libnl_ver=0
 PKG_CHECK_MODULES(