This patch removes deferred error string formatting: now we do it during
SDL_SetError(), so there's no limit on printf-style arguments used.
Also removes stub for managing error string translations; we don't have the
facilities to maintain that and the way we set arbitrary error strings
doesn't really make this practical anyhow.
Since the final error string is set right away and unique to the thread,
we no longer need a static buffer for legacy SDL_GetError(), and we don't
have to allocate 5x 128-byte argument fields per-thread. Also, since we now
use SDL_vsnprintf instead of parsing the format string ourselves, there's a
lot of code deleted and we have access to more robust formatting powers now.
This does mean the final error strings can't be more than 128 bytes, down
from the theoretical maximum of around 768, but I think this is probably okay.
They might truncate but they will always be null-terminated!
Fixes Bugzilla #5092.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().