Fixed crash if initialization of EGL failed but was tried again later.

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().

visualtest/testsprite2_sample.parameters

@@ -0,0 +1,29 @@
+# parameter name, type, value range, required, categories
+--gldebug, boolean, [], false, []
+--info, enum, [all video modes render event], false, []
+--log, enum, [all error system audio video render input], false, []
+--display, integer, [1 5], false, []
+--fullscreen, boolean, [], false, []
+--fullscreen-desktop, boolean, [], false, []
+# --windows, integer, [1 5], false, [] # this option is not supported yet
+--title, enum, [vartest bartest footest], false, []
+--icon, enum, [icon.bmp], false, []
+--center, boolean, [], false, []
+--position, enum, [300,300], false, []
+--geometry, enum, [500x500], false, []
+--min-geometry, enum, [100x100], false, []
+--max-geometry, enum, [600x600 700x700], false, []
+--logical, enum, [500x500 550x450], false, []
+--scale, integer, [1 5], false, []
+--depth, integer, [1 5], false, []
+--refresh, integer, [1 5], false, []
+--vsync, boolean, [], false, []
+--noframe, boolean, [], false, []
+--resize, boolean, [], false, []
+--minimize, boolean, [], false, []
+--maximize, boolean, [], false, []
+--grab, boolean, [], false, [mouse]
+--blend, enum, [none blend add mod], false, []
+--cyclecolor, boolean, [], false, []
+--cyclealpha, boolean, [], false, []
+--iterations, integer, [10 100], false, []