Remove g++ and git-svn from install-build-deps.sh

The build hasn't used gcc for a long time now, and we've been
off svn for a while as well.

Bug: none
Change-Id: I3c90b7395bec146dc29bd86b869d55e1f68550fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1763872
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#689076}

build/install-build-deps.sh

@@ -156,9 +156,7 @@ dev_list="\
   devscripts
   fakeroot
   flex
-  g++
   git-core
-  git-svn
   gperf
   libappindicator3-dev
   libasound2-dev
@@ -297,6 +295,8 @@ backwards_compatible_list="\
   fonts-stix
   fonts-thai-tlwg
   fonts-tlwg-garuda
+  g++
+  git-svn
   language-pack-da
   language-pack-fr
   language-pack-he