Don't pass unnecessary -Wno-format to Python bindings

Fixes FTBFS on gcc7

brltty-format-security.patch

@@ -0,0 +1,11 @@
+--- configure.orig	2017-03-17 10:38:18.549098316 -0400
++++ configure	2017-03-17 10:38:26.499963667 -0400
+@@ -8673,7 +8673,7 @@
+ 
+ if test "${GCC}" = "yes"
+ then
+-   CYTHON_CFLAGS="-Wno-parentheses -Wno-unused -Wno-format -fno-strict-aliasing -U_POSIX_C_SOURCE -U_XOPEN_SOURCE"
++   CYTHON_CFLAGS="-Wno-parentheses -Wno-unused -fno-strict-aliasing -U_POSIX_C_SOURCE -U_XOPEN_SOURCE"
+ else
+    case "${host_os}"
+    in

brltty.spec

@@ -22,7 +22,7 @@
 
 Name: brltty
 Version: %{pkg_version}
-Release: 7%{?dist}
+Release: 8%{?dist}
 License: GPLv2+
 Group: System Environment/Daemons
 URL: http://mielke.cc/brltty/
@@ -33,6 +33,9 @@ Patch1: brltty-loadLibrary.patch
 Patch2: brltty-5.0-libspeechd.patch
 # https://bugzilla.redhat.com/show_bug.cgi?id=1392147
 Patch3: brltty-ocaml-4-04-fix.patch
+# Don't pass unnecessary -Wno-format
+# Submitted to upstream: https://github.com/brltty/brltty/pull/91
+Patch4: brltty-format-security.patch
 Summary: Braille display driver for Linux/Unix
 BuildRequires: byacc, glibc-kernheaders, bluez-libs-devel, systemd
 BuildRequires: gettext, at-spi2-core-devel, espeak-devel
@@ -200,6 +203,7 @@ This package provides the OCaml binding for BrlAPI.
 %patch1 -p1 -b .loadLibrary
 %patch2 -p1 -b .libspeechd
 %patch3 -p1 -b .ocaml-4-04
+%patch4 -p0 -b .format-sec
 
 # remove packaged binary file
 rm -f Programs/brltty-ktb
@@ -420,6 +424,10 @@ fi
 %endif
 
 %changelog
+* Fri Mar 17 2017 Stephen Gallagher <sgallagh@redhat.com> - 5.4-8
+- Don't pass unnecessary -Wno-format to Python bindings
+- Fixes FTBFS on gcc7
+
 * Fri Feb 10 2017 Fedora Release Engineering <releng@fedoraproject.org> - 5.4-7
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_26_Mass_Rebuild