Fix-ups for prebuilt Chromium

- Make copying far more reliable, even on non-clean builds
- Use $OUT in script in all cases, apparently get_build_var OUT_DIR isn't reliable.
envsetup.sh, please -_-

Change-Id: I6e33a97fb3d1d39ee679fcc695360e543f59877f
Merge github.com:TeamBliss-LP/android_vendor_bliss into lp5.0