[NetworkManager-fortisslvpn] build: call AC_USE_SYSTEM_EXTENSIONS before AC_COMPILE_IFELSE

[Lubomir Rintel <lkundrak src gnome org>]

commit c5a9052361d802167a0c25f079a2bda1641fdf8a
Author: Lubomir Rintel <lkundrak v3 sk>
Date:   Wed Mar 20 12:19:55 2019 +0100

    build: call AC_USE_SYSTEM_EXTENSIONS before AC_COMPILE_IFELSE
    
    Otherwise autoconf warns.

 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index c1963a1..e89648e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -8,8 +8,8 @@ AM_INIT_AUTOMAKE([1.9 no-dist-gzip dist-xz -Wno-portability])
 AM_MAINTAINER_MODE
 AM_SILENT_RULES([yes])
 
+AC_USE_SYSTEM_EXTENSIONS
 AC_CONFIG_MACRO_DIR([m4])
-
 AC_CONFIG_HEADERS([config.h])
 
 dnl