Allow releaseCallback to be null in JavaI420Buffer#wrap.
Allow releaseCallback to be null in JavaI420Buffer#wrap.

R=magjed

Bug: None
Change-Id: I3d57198dd0b8e0575af61b0dac439e3753a2360a
Reviewed-on: https://webrtc-review.googlesource.com/92386
Reviewed-by: Magnus Jedvert <9507adee858471ab168c339dc72b814b168c081b@webrtc.org>
Commit-Queue: Sami Kalliomäki <b9debeb8943b89663e00c95863751401cba91c9a@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#24193}
ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc