Upgrade libcups to v2.3.1

Local changes:
1. Makes _cupsSetHTTPError visible because it is used in
BuiltInPrintService.
2. Adds config.h and cups/tls-boringssl.c.

Exempt-From-Owner-Approval: upgrade
Change-Id: Iabc33a8248ee1441333ab0e0ace8cf1965a5b866
diff --git a/templates/class-jobs-header.tmpl b/templates/class-jobs-header.tmpl
new file mode 100644
index 0000000..61e5151
--- /dev/null
+++ b/templates/class-jobs-header.tmpl
@@ -0,0 +1 @@
+<H3 CLASS="title">Jobs</H3>