Update Buck to recent version

This version fixes this bug [1] that allows us to eliminate these ugly
shell backticks and switch again to escaped macro like invocations:

  \$(dirname $OUT)

[1] https://github.com/facebook/buck/issues/212

Change-Id: Ie43b3ff6dfc89c4d840f2ff75c64ac0a5c6346b6
4 files changed