Rather than inspecting CMAKE_BUILD_TYPE manually and setting
DEBUG_OPTIONS based off the results, set CMAKE_{C/CXX}_FLAGS_DEBUG,
and allow that to be picked up by CMake #565. Remove repeated -W
flags that were all over the place, making them global compiler
flags. Remove repeated FORTIFY=2 definition that was all over the
place, making it a global compiler definition. Remove all uses of
${DEBUG_FLAGS}. Also, since CMake doesn't define a CMAKE_BUILD_TYPE
by default, instead just setting neither debugging nor optimization
flags, in what seems a pretty fucking boneheaded move, set it by
default to RelWithDebInfo. ugh. Explicitly disuse unused PoC variables.
Unify ffmpeg/oiio/null implementations, where possible. This effectively
required placing all three in the same file, which meant they're all now
C++. Update FFmpeg implemenation to be C++-usable. Implement
ncvisual_rotate_cw() and ncvisual_rotate_ccw() #515. Move most of tetris
over to Visual from Plane #558. Add bgra_to_rgba(), necessary for
creating ncvisual from BGRA memory. Implement ncvisual_from_rgba()
and ncvisual_from_bgra() #557. Add unit tests on ncvisual rotation.
Added:
* class FDPlane (`ncfdplane*`)
* class Subproc (`ncsubproc*`)
* NotCurses: get_inputready_fd (`notcurses_inputready_fd`)
* Plane: qrcode (`ncplane_qrcode`)
* class PlotBase: templated base class for Plot variations
* class PlotU: `uint64_t` instantiation of PlotBase (aliased to previous
`Plot` class for source compatibility), `ncuplot*`
* class PlotD: `double` instantiation of PlotBase, `ncdplot*`
We need support three distinct paths for destruction of
ncsubprocs: (1) external call to ncsubproc_destroy() while
the subprocess is running, (2) external call to
ncsubproc_destroy() after the subprocess has terminated, and
(3) internal call to ncsubproc_destroy() without any external
call. To do this properly, we always waitid() on the subprocess
in our ncsubproc thread, and do not cancel said thread. This
guarantees that the subprocess has been reaped if the thread
has exited. We throw a pidfd_send_signal() into the thread
prior to the waitid(), because this is safe with pidfds. The
thread reclaims no resources otherwise. ncsubproc_destroy(),
instead, reclaims them, after joining the ncsubproc thread.
It sends SIGKILL before the join, which is once again safe
thanks to pidfds. Resolves#552.
