am b23451d0: am 3a9aa008: am def30fc2: Clarify the use of --boot-dirs in the header comment.

Merge commit 'b23451d0c40d6a8f49b47ce57601fafc23b4958c' into dalvik-dev

* commit 'b23451d0c40d6a8f49b47ce57601fafc23b4958c':