time support: check and define NDN_CPP_HAVE_GMTIME_SUPPORT. In ndn_toIsoString and ndn_fromIsoString, return an error if not supported.
diff --git a/include/config.h.in b/include/config.h.in
index 203a519..7621126 100644
--- a/include/config.h.in
+++ b/include/config.h.in
@@ -12,6 +12,12 @@
/* Define to 1 if you have the <dlfcn.h> header file. */
#undef HAVE_DLFCN_H
+/* Define to 1 if you have the `gettimeofday' function. */
+#undef HAVE_GETTIMEOFDAY
+
+/* 1 if have sys/time gmtime support including timegm. */
+#undef HAVE_GMTIME_SUPPORT
+
/* Define to 1 if you have the <inttypes.h> header file. */
#undef HAVE_INTTYPES_H
@@ -39,6 +45,9 @@
/* Have the SQLITE3 library */
#undef HAVE_SQLITE3
+/* Define to 1 if you have the `sscanf' function. */
+#undef HAVE_SSCANF
+
/* Define to 1 if you have the <stdint.h> header file. */
#undef HAVE_STDINT_H
@@ -51,6 +60,9 @@
/* 1 if have the `std::shared_ptr' class. */
#undef HAVE_STD_SHARED_PTR
+/* Define to 1 if you have the `strchr' function. */
+#undef HAVE_STRCHR
+
/* Define to 1 if you have the <strings.h> header file. */
#undef HAVE_STRINGS_H
@@ -60,6 +72,9 @@
/* Define to 1 if you have the <sys/stat.h> header file. */
#undef HAVE_SYS_STAT_H
+/* Define to 1 if you have the <sys/time.h> header file. */
+#undef HAVE_SYS_TIME_H
+
/* Define to 1 if you have the <sys/types.h> header file. */
#undef HAVE_SYS_TYPES_H