Fix Xwayland dma-buf leak: close Zink's emulated GEM handles on KGSL (#275)

Close Zink's emulated GEM handles on KGSL (Xwayland dma-buf leak)

The session preload hands out GEM handles on the KGSL render node by
duplicating the dma-buf descriptor, and released them only through
drmCloseBufferHandle. Zink gives handles back with
drmIoctl(DRM_IOCTL_GEM_CLOSE) instead, which KGSL refuses, so every
duplicated descriptor stayed open and kept its buffer alive.

Xwayland asks for a handle for each buffer it imports through gbm. With
"Force game windows fullscreen" fighting a game's own resolution
(DiRT 3 at 1280x720), the game recreates its swapchain many times a
second and Xwayland piled up ~2,000 old swapchain images (6+ GB) in
seconds until Android killed the session. A preload trace on the device
put 2,090 of 2,118 open dma-buf descriptors in Xwayland on
drmPrimeFDToHandle called from Zink.

Handle GEM_CLOSE on the KGSL node in drmIoctl, and check the three DRM
symbols are exported in CI.

Co-authored-by: The412Banner <[email protected]>

.github/workflows/build.yml

@@ -343,7 +343,7 @@ jobs:
             echo "::error::libfakeinput.so exports the C++ runtime"; exit 1
           fi
           SESSION=$(syms "$D/libblsession.so")
-          for sym in socket bind getsockname setsockopt statfs statvfs syscall shm_open shm_unlink mmap mmap64 munmap; do
+          for sym in socket bind getsockname setsockopt statfs statvfs syscall shm_open shm_unlink mmap mmap64 munmap drmPrimeFDToHandle drmCloseBufferHandle drmIoctl; do
             grep -qx "$sym" <<<"$SESSION" || { echo "::error::libblsession.so does not export $sym"; exit 1; }
           done
           test -f "$D/usr/local/bin/droiddeck-session"