stagefright: Move NULL check

We switch our NULL check to before we dereference 'buffer' for
the range_length().  This allows a debug build with a bad state
to have things caught via CHECK instead of a crash.

Test: Treehugger
Change-Id: Iae3a6a9e90ec91962dc0e9bebcac075cf1d7d4c1
1 file changed