Bug 40764: Embed repo URL and git revision in Firefox

They will be visible and clickable in about:buildconfig.

projects/firefox/config

@@ -18,6 +18,8 @@ var:
   branding_directory_prefix: 'tb'
   copyright_year: '[% exec("git show -s --format=%ci").remove("-.*") %]'
   nightly_updates_osname: '[% c("var/osname") %]'
+  gitlab_project: https://gitlab.torproject.org/tpo/applications/tor-browser
+  git_commit: '[% exec("git rev-parse HEAD") %]'
   deps:
     - build-essential
     - unzip
@@ -74,6 +76,7 @@ targets:
     var:
       branding_directory_prefix: 'pb'
       browser_branch: '12.0-1'
+      gitlab_project: https://gitlab.torproject.org/tpo/applications/privacy-browser
 
   linux-x86_64:
     var:

projects/firefox/mozconfig

@@ -73,3 +73,6 @@
 
 mk_add_options MOZ_PARALLEL_BUILD=[% c("num_procs") %]
 
+export MOZ_INCLUDE_SOURCE_INFO=1
+export MOZ_SOURCE_REPO="[% c('var/gitlab_project') %]"
+export MOZ_SOURCE_CHANGESET=[% c("var/git_commit") %]