This change adds support for saving and loading the contents of the EGL
cache. It also adds some simple tests for the EGL cache.
Change-Id: I18e5e789e0897a0783d29d1c1e64d26de2dd44c4
as specified by the EGL specification, terminated objects's
handles become invalid, the objects themselves are destroyed
when they're not current to some thread.
Change-Id: Id3a4a5736a5bbc3926a9ae8385d43772edb88eeb