Add src/vlib/config.h.in template

Change-Id: I9b81dcb9250cab09b88f161366da9475a7ee5dd6
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/configure.ac b/src/configure.ac
index 2d12090..f6ec44b 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -3,7 +3,14 @@
 AC_CONFIG_AUX_DIR([.])
 AM_INIT_AUTOMAKE([subdir-objects])
 AM_SILENT_RULES([yes])
-AC_CONFIG_FILES([Makefile plugins/Makefile vpp-api/python/Makefile vpp-api/java/Makefile vpp-api/vapi/Makefile])
+AC_CONFIG_FILES([ \
+  Makefile \
+  plugins/Makefile \
+  vpp-api/python/Makefile \
+  vpp-api/java/Makefile \
+  vpp-api/vapi/Makefile \
+  vlib/config.h \
+])
 AC_CONFIG_MACRO_DIR([m4])
 
 AC_PROG_CC