autogen.sh: Ignore autoconf warnings on FreeBSD

Prevents "upstream" issues like:

fk@r500 ~/git/tlsdate $./autogen.sh
autoreconf-2.69: Entering directory `.'
autoreconf-2.69: configure.ac: not using Gettext
autoreconf-2.69: running: aclocal --force -I m4
aclocal-1.12: warnings are treated as errors
/usr/local/share/aclocal/libxosd.m4:9: warning: underquoted definition of AM_PATH_LIBXOSD
/usr/local/share/aclocal/libxosd.m4:9:   run info Automake 'Extending aclocal'
/usr/local/share/aclocal/libxosd.m4:9:   or see http://www.gnu.org/software/automake/manual/automake.html#Extending-aclocal
autoreconf-2.69: aclocal failed with exit status: 1

1 files changed, 5 insertions, 3 deletions

diff --git a/autogen.sh b/autogen.sh
index bd7a15f..c014aee 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -10,8 +10,10 @@ if [ ! -d config ];
 then
   mkdir config;
 fi
-
-WARNINGS="all,error"
-export WARNINGS
+if [ $(uname) != FreeBSD ];
+then
+  WARNINGS="all,error"
+  export WARNINGS
+fi
 
 autoreconf --install --verbose --force