libstagefright: fix 64-bit warnings

%lld -> %" PRId64 " for int64_t
%d -> %zu for size_t
Also fixes some casts from void* to integer types, and some comparisons
between signed and unsigned.

(cherry picked from commit b4a7a2df)

Change-Id: I76ba94d0b67776fd7abdc83b43d47c61d6c32f4c