graphics: add a default implementation to IAllocator

The default implementatoin is built on top of conventional gralloc1.

This also adds a static library, libgralloc1-adapter.  It is intended to
ease the porting of gralloc0 to gralloc1.

Test: booted to launcher, tested with YouTube and some games.

Change-Id: Id640b1d5a1e1eea1aafabb6c134e6be6e71afff5