PSA: third_party/minijail repo URL change

[Daniel Verkamp]

Run this command in the crosvm directory to update to the new submodule URL:

git submodule update --init --force

... if you encounter this problem when updating your crosvm checkout:

error: RPC failed; HTTP 400 curl 22 The requested URL returned error: 400
fatal: expected 'acknowledgments'
Errors during submodule fetch:
third_party/minijail

The minijail repository (which crosvm includes as a submodule) has
moved from the Android git host to Chromium, and we have updated our
submodule to match.

Thanks,
-- Daniel