Roll buildtools b0ede9c8:b73e4f70 to roll GN 66e43703:63d951b0 (328870:329298)

This picks up the following change:

  22d6ca18 GN: Don't generate phony rules called "all".

TBR=brettw@chromium.org
CQ_EXTRA_TRYBOTS=tryserver.chromium.mac:mac_chromium_gn_rel;tryserver.chromium.win:win8_chromium_gn_rel

Review URL: https://codereview.chromium.org/1141483002

Cr-Commit-Position: refs/heads/master@{#329328}

DEPS

@@ -62,7 +62,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.
-  'buildtools_revision': 'b0ede9c89f9d5fbe5387d961ad4c0ec665b6c821',
+  'buildtools_revision': 'b73e5f70d7ac6be98fb2555461f631afc90216ce',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.