X11 seemed to be confused by the broad definition, so WEIGHT_NAME,
SLANT and SETWIDTH_NAME were defined, thus fixing the font lookup
on some systems (tested on Mageia 6 with X11 1.19.1).
Fixes bug 3571.
This relies on a successful SDL_Init(SDL_INIT_VIDEO) to work, since it's
silly to reproduce all the Xinerama/XRandR code in the message box parts. If
X11 is available but SDL hasn't been initialized, the message box will center
in the primary screen, which will be positioned weirdly on multi-head setups,
but this should fix the most significant common case.
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().
