Subframe openjpeg encoder fixes

This MR is a subset of !1654 (closed) to ease the review and let the multithreaded part in his own MR.

Author: Aaron Boxer aaron.boxer@collabora.com Date: Thu Apr 16 10:06:29 2020 -0400

openjpegenc: store stripe offset when encoding image

The decoder can simply read this offset after decoding
to know where to blit the stripe to the full frame

commit 67426d68 Author: Aaron Boxer aaron.boxer@collabora.com Date: Tue Mar 24 09:15:30 2020 -0400

openjpegenc: take subsampling into account when calculating stripe height

We calculate minimum of (stripe height * sub sampling) across all components
to ensure that all component dimensions are consistent with sub-sampling.
The last stripe for each component is simply the remaining height.

limit wavelet resolutions for "thin" stripes

commit b3513e11 Author: Stéphane Cerveau scerveau@collabora.com Date: Thu Mar 12 13:41:40 2020 +0100

openjpegenc: fix memory leak from mstream

commit 3fa7d556 Author: Aaron Boxer aaron.boxer@collabora.com Date: Mon Jan 13 14:00:38 2020 -0500

openjpegenc: fail negotation in handle_frame if alignment mismatch

If encoder is in stripe mode, then downstream must also support stripe