[SDL] error removal patch for SDL_x11dyn.c

[Ryan C. Gordon]

> I found that calling SDL_GetError when an error hasn't necessarily occurred is
> still reporting problems from loadso regarding dynamic functions in X11.  I've
> added the following to my local copy to avoid revealing the 'many library
> lookup' approach adopted by x11dyn.c:

Something roughly like this just went into Subversion (revision #3064 
for 1.2, #3065 for 1.3).

If anyone finds more cases where we're setting error messages for APIs 
that succeed in this way, let me know...there are probably a lot of 
these in SDL, and it will take a long time to weed them all out, but it 
would be nice to fix them all over time.

--ryan.