Remove stale clang prebuilts

Removing clang-2812033.
Removing clang-3289846.
Removing clang-3688880.

We don't need to keep clang-3289846, unlike the platform, since the NDK
is already ahead there, and we only use these windows prebuilts for the
NDK itself.

Test: Verified NDK is only using clang-3362437.
Change-Id: I91cddb39ff74c0910a1d21ad1e384b7ee18fdaa8
493 files changed
tree: 0a8e58c3f1df80eb2af15f44a20ef8cec19c330b
  1. clang-3362437/
  2. clang-3859424/