Change UpdateService POST URI

As d01e32c3786f2fbbb70c9724a87cf979b4a06232 found, the Redfish
specification doesn't allow a direct POST handler on UpdateService.
Ideally clients would be following the specification, and relying on
the HttpPushUri as the spec requires, so we could simply make this
change.  Unfortunately, a quick polling of the community shows that a
significant number of instances, including the Redfish cheat sheet, and
the robot tests, have hardcoded the non-spec behavior.  This commit is
present to give a trap door to allow easier porting of this behavior to
the specification.

The old uri is left, and now returns a WARNING http field, indicating
that the uri is deprecated, in case clients have ignored the Redfish
specification.

Tested:
Ran firmware update instructions from
https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/53664

Test gave the same result as previously.

/redfish/v1/UpdateService returns an HttpPushUri that matches the above.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I7427f461d151c9460160b0b9b366dca5aefc49d5
diff --git a/meson.build b/meson.build
index 0ab48ff..d51d9b8 100644
--- a/meson.build
+++ b/meson.build
@@ -80,6 +80,7 @@
   'redfish-host-logger'                         : '-DBMCWEB_ENABLE_REDFISH_HOST_LOGGER',
   'redfish-new-powersubsystem-thermalsubsystem' : '-DBMCWEB_NEW_POWERSUBSYSTEM_THERMALSUBSYSTEM',
   'redfish-provisioning-feature'                : '-DBMCWEB_ENABLE_REDFISH_PROVISIONING_FEATURE',
+  'redfish-post-to-old-updateservice'           : '-DBMCWEB_ENABLE_REDFISH_UPDATESERVICE_OLD_POST_URL',
   'redfish'                                     : '-DBMCWEB_ENABLE_REDFISH',
   'rest'                                        : '-DBMCWEB_ENABLE_DBUS_REST',
   'session-auth'                                : '-DBMCWEB_ENABLE_SESSION_AUTHENTICATION',