[interchange] Add x_accel_expires pragma to set X-Accel-Expires header

[Jon Jensen]

commit 6157e62565e7a076db20d76ca2643f3d4d8a53c5
Author: Jon Jensen <jon at endpoint.com>
Date:   Tue Jan 16 16:39:58 2018 -0700

    Add x_accel_expires pragma to set X-Accel-Expires header
    
    This allows us to have an nginx proxy cache responses for a different
    length of time than the end client will based on the Cache-Control
    header. For details see:
    
    http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_valid

 lib/Vend/Server.pm |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/lib/Vend/Server.pm b/lib/Vend/Server.pm
index 3bb495d..473e47f 100644
--- a/lib/Vend/Server.pm
+++ b/lib/Vend/Server.pm
@@ -1,6 +1,6 @@
 # Vend::Server - Listen for Interchange CGI requests as a background server
 #
-# Copyright (C) 2002-2016 Interchange Development Group
+# Copyright (C) 2002-2018 Interchange Development Group
 # Copyright (C) 1996-2002 Red Hat, Inc.
 #
 # This program was originally based on Vend 0.2 and 0.3
@@ -24,7 +24,7 @@
 package Vend::Server;
 
 use vars qw($VERSION $Has_JSON $RUNDIR);
-$VERSION = '2.108';
+$VERSION = '2.109';
 
 use Cwd;
 use POSIX qw(setsid strftime);
@@ -643,6 +643,9 @@ sub get_cache_headers {
 	my $cc = $::Pragma->{cache_control};
 	push @headers, "Cache-Control: $cc" if $cc;
 
+	my $xee = $::Pragma->{x_accel_expires};
+	push @headers, "X-Accel-Expires: $xee" if defined($xee) and length($xee);
+
 	push @headers, "Pragma: no-cache" if delete $::Scratch->{mv_no_cache};
 
 	return @headers;