Fix deadlock when cleaning objects in eglTerminate

When eglTerminate() is called with a window surface still exists, a
deadlock would occur since egl_display_t::terminate() holds a lock
while destroying the window surface, which calls
onWindowSurfaceDestroyed() which attempts to take the same lock.

This change refactors the hibernation code and data into a separate
object with its own lock, separate from the egl_display_t lock. This
avoids the deadlock and better encapsulates the hibernation logic.

The change also fixes a bug discovered incidentally while debugging:
hibernating after calling eglTerminate() succeeds, but will cause
awakens from subsequent eglInitialize() to fail. We will no longer
hibernate a terminated display.

Change-Id: If55e5bb603d4f8953babc439ffc8d8a60af103d9