log: support syslog()

Allow logging to syslog if log_file is configured to "syslog".

configure.ac

@@ -54,6 +54,21 @@ if test -z "$prefix" || test "x$prefix" = xNONE; then
 fi
 
 
+dnl
+dnl libc features
+dnl
+
+AC_CHECK_FUNCS(syslog)
+if test $ac_cv_func_syslog = no; then
+	# syslog is not in the default libraries.  See if it's in some other.
+	for lib in bsd socket inet; do
+		AC_CHECK_LIB($lib, syslog,
+			[AC_DEFINE(HAVE_SYSLOG)
+			LIBS="$LIBS -l$lib"; break])
+	done
+fi
+
+
 dnl
 dnl build options
 dnl