configure.ac: Add AC_SYS_LARGEFILE

Making sure large file support is enabled across the tree even on 32-bit
systems.

Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
diff --git a/configure.ac b/configure.ac
index aa7d1f2..9d2ddb4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -57,6 +57,8 @@
 AC_PROG_SED
 AC_PROG_MKDIR_P
 
+AC_SYS_LARGEFILE
+
 LT_PREREQ([2.2])
 LT_INIT([disable-static])