Because of the android sdk managed by CIPD (see go/use-adjective-apis),
its deps repo ndk needs to be relocated to third_party/android_ndk.
This CL changes the ndk root path in files in v8.

Bug: chromium:659808
Change-Id: I78d534cbb81eebd1dc631293d54764f027ed0567
Reviewed-on: https://chromium-review.googlesource.com/861182Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50493}