283c5e7ea8
This patch was made to guard Update functionality from being called in BrowserGlue.jsm if Firefox was not built with support for the Updater. However, it also ended up touching the updater build configuration. I discovered while testing this patch that building with `--disable-updater` does not imply `--disable-maintenance-service` or `--disable-update-agent`. So I fixed that issue as well. Once that was fixed, I could change some other code that checked `AppConstants.MOZ_UPDATER && AppConstants.MOZ_UPDATE_AGENT` since that is now equivilant to `AppConstants.MOZ_UPDATE_AGENT`. Differential Revision: https://phabricator.services.mozilla.com/D156902