Move GC daemon locking logic into heap

Fixes deadlock caused by acquirng the mutator lock while
synchronizing on the daemon thread.

Bug: 18739541
Change-Id: Ib3ac3788081d3d471195a6e3a8ed163237616a4f
Remove unnecessary include directives.

These are all picked up by virtue of the libraries that we use.

Change-Id: Ib5e86c65d53f3448d5f1d0c0d24f0f63ef5f1868
Merge "Move GC daemon locking logic into heap"
Merge "Remove unnecessary include directives."