opengl: use buffer objects instead of host memory for subpictures

See bbbc51c713432b25b0ffdfa943b8441aa7d4f96e
mp4: fix pointer type
decoder: fix debug message
http_auth: fix debug message on 64-bits architectures

The * modifier expects an int. A pointer difference is ptrdiff_t.
mpeg: fix warning
mkv: check for overflow and fix type limit warning
xspf: fix type limit warning
transcode: fix parameter warning
fourcc: add missing initializers
gme: fix warning
ts: fix warning
transcode: copy video orientation to encoder
mp4 mux: encode video orientation
avcodec encoder: get bytes per pixel from context if needed

Falling back to 3 bytes broke the buffer allocation for BMP with ffmpeg, which
defaults to RGBA.

Fixes #9687
macosx: Fix startup delays by loading Open.nib only on demand

There is no need to already load it here, not every user uses the open panel.
Additionally, input devices listing may take one or two seconds the
first time after the system started, so this is also better done only when needed.

close #11098
macosx: avoid ugly delayed initialization calls for the open panel

These selectors may not be called in time as the main loop is blocked
if a modal dialog is open.
macosx: load core dialog nib on demand
macosx: simplifications
demux: mp4: fix condition

is array, not variable.
cid #1194828
avio: fix busy loop on EOF (fixes #11076)