[gspell] build: silence non-portability warnings

[Sébastien Wilmet <swilmet src gnome org>]

commit 615d8981fb8a7012db7bea89b25bf238d1b69b89
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sun Mar 13 11:52:04 2016 +0100

    build: silence non-portability warnings

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 4ee1d68..e2741c8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -54,7 +54,7 @@ AC_CONFIG_HEADER([config.h])
 AC_CONFIG_MACRO_DIR([m4])
 
 # gnu strictness to generate the INSTALL file
-AM_INIT_AUTOMAKE([1.11 tar-ustar dist-xz no-dist-gzip gnu])
+AM_INIT_AUTOMAKE([1.11 tar-ustar dist-xz no-dist-gzip gnu -Wno-portability])
 
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])