configure.ac: enable largefile support if possible

https://bugzilla.gnome.org/show_bug.cgi?id=793103
diff --git a/configure.ac b/configure.ac
index 2aebba0..fd4a4e2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -101,6 +101,12 @@
 dnl Determine endianness
 AC_C_BIGENDIAN
 
+dnl *** software ***
+
+dnl check for large file support
+dnl affected plugins must include config.h
+AC_SYS_LARGEFILE
+
 dnl *** checks for programs ***
 
 dnl find a compiler