Extend apexer's tools search path to SDK prebuilts.

In particular, this enables apexer to be used with a master-art source
tree, by using aapt2 from SDK prebuilts instead of building it, which
requires the following build dependencies (which are not part of the
master-art manifest):
- external/libpng
- external/robolectric-shadows
- frameworks/base
- frameworks/opt/setupwizard

Test: system/apex/apexer/runtests.sh on a master-art source tree
Bug: 113373927
Bug: 112458021
Change-Id: Ice7a2923a6113c73082b60da96621f92ca59cb09
3 files changed
tree: 31c2b73306221fa2fd55dc69183d5de65841eb20
  1. apexd/
  2. apexer/
  3. build/
  4. OWNERS
  5. PREUPLOAD.cfg