date_Decrement: change assert so it doesn't to funky stuff

If we do date_Set and right after that date_Decrement that assert
seemed to behave differently in 64bit and 32bit architectures.

Ref #9022, #10101
transcode: handle acodec aliases properly

Get correct fourcc for i_acodec instead creating fourcc directly from
user input.

Fixes #9755
Qt4: improve macro expansion safety
Qt4: refactor
Qt4: fix fullscreen and video-on-top toggle across input or video reset
vout: pass enum for window state instead of boolean (refs #10302)
vout: add proper core-managed object variable for wall paper mode
XCB: remove wall-paper mode legacy hacks
Direct3D: remove wall-paper playlist hack

This is now managed by the playlist and video output core.
DirectDraw: remove wall-paper playlist hack
qt4: update wall-paper mode toggling
hotkeys: fix wall-paper toggling
Lua: remove cargo cult check for the private data of the input thread
Cosmetic
Lua: do not call luaopen_volume() twice for interfaces
Lua: check vlclua_get_playlist_internal() for NULL
Lua: set playlist object explicitly in state
v4l2: fix frequency conversion from Hz (fixes #10309)
audioscrobbler: simplify pl_Get() usage
ncurses: pass interface thread pointer to pl_Get() directly