autoconf: add -Werror to libutil.h header check

libutil.h is only needed on BSDs, but not in Linux. Debian package
libbsd-dev-0.3.0-1 installed a libutil.h overlay that contains a

Perform the libutil.h check with -Werror, so we don't include this
bogus header.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

xen-unstable changeset: 26005:cdb48f1742f3
Backport-requested-by: Ian Campbell <Ian.Campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

2 files changed, 14 insertions, 0 deletions

diff --git a/tools/configure b/tools/configure
index d68d985bed..709204330a 100755
--- a/tools/configure
+++ b/tools/configure
@@ -6543,6 +6543,10 @@ $as_echo "$ax_cv_pthread_flags" >&6; }
 
 
 
+
+    saved_CPPFLAGS="$CPPFLAGS"
+
+    CPPFLAGS="$CPPFLAGS -Werror"
     ac_fn_c_check_header_mongrel "$LINENO" "libutil.h" "ac_cv_header_libutil_h" "$ac_includes_default"
 if test "x$ac_cv_header_libutil_h" = x""yes; then :
 
@@ -6553,6 +6557,9 @@ $as_echo "#define INCLUDE_LIBUTIL_H <libutil.h>" >>confdefs.h
 fi
 
 
+
+    CPPFLAGS="$saved_CPPFLAGS"
+
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for openpty et al" >&5
 $as_echo_n "checking for openpty et al... " >&6; }
 if test "${ax_cv_ptyfuncs_libs+set}" = set; then :
diff --git a/tools/m4/ptyfuncs.m4 b/tools/m4/ptyfuncs.m4
index bfea3e10b7..3e37b5a23c 100644
--- a/tools/m4/ptyfuncs.m4
+++ b/tools/m4/ptyfuncs.m4
@@ -1,7 +1,14 @@
 AC_DEFUN([AX_CHECK_PTYFUNCS], [
+    dnl This is a workaround for a bug in Debian package
+    dnl libbsd-dev-0.3.0-1. Once we no longer support that
+    dnl package we can remove the addition of -Werror to
+    dnl CPPFLAGS.
+    AX_SAVEVAR_SAVE(CPPFLAGS)
+    CPPFLAGS="$CPPFLAGS -Werror"
     AC_CHECK_HEADER([libutil.h],[
       AC_DEFINE([INCLUDE_LIBUTIL_H],[<libutil.h>],[libutil header file name])
     ])
+    AX_SAVEVAR_RESTORE(CPPFLAGS)
     AC_CACHE_CHECK([for openpty et al], [ax_cv_ptyfuncs_libs], [
         for ax_cv_ptyfuncs_libs in -lutil "" NOT_FOUND; do
             if test "x$ax_cv_ptyfuncs_libs" = "xNOT_FOUND"; then