libstagefright: Handle error on allocate buffer failure

Set state to error on allocate buffer failure at start(init)
of decoding.

CRs-Fixed: 332373
(cherry picked from commit c7a957b7595fff44f9242ddcd3eeeabe827f9639)

Change-Id: If0796250c6385df28e3545c08e90e1626ff5e709