Deprecate installing 32bit build dependencies on a 64bit

Deprecate installing 32bit build dependencies on a 64bit
system. Instead, point the developer towards the install-chroot.sh
script, which is a cleaner way to achieve the same goal.

BUG=none
TEST=none
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=126989

[tony, 2012-03-15 20:45:56]

LGTM

https://chromiumcodereview.appspot.com/9706076/diff/1/build/install-build-dep...
File build/install-build-deps.sh (right):

https://chromiumcodereview.appspot.com/9706076/diff/1/build/install-build-dep...
build/install-build-deps.sh:221: echo "install-build-deps.sh. N.B. this code is
no longer maintained"
Nit: It seems a bit spammy to echo all of this every time the user runs
install-build-deps.sh.  This part seems fine (lines 219-221).  I would only
print the rest of it when the user passes in --lib32.

[Markus (顧孟勤), 2012-03-15 20:56:19]

Changed the warning, so it will only be displayed if you actually
attempt to install 32bit libraries. Hopefully, this turns out to be
a good compromise between not being overly verbose and still steering
users the right direction. If we start seeing problems, we can always
tweak the wording.

[tony, 2012-03-15 22:03:04]

LGTM