Bug fix release for the 0.34 branch.

Fixes and Minor Enhancements

• player: fix autofit/geometry related segfault
• ao_oss: add missing PATH_DEV_MIXER define
• egl_helpers: fix context creation if GLES 3 is not available
• audio: stop corrupting audio on underreads
• wayland: fix a potential segfault on surface enter
• vo_gpu: opengl: fix wrong glMemoryBarrier call
• vo_gpu: opengl: create context at version 4.4 again
• af_lavcac3enc: fix memory leak on no-op
• subprocess: unblock/reset signals before running child process
• wayland: avoid doing unneccesary window resizes