egl: SDL_EGL_LoadLibaryOnly() shouldn't set _this->gl_config.driver_loaded = 1

This is handled in in the higher-level SDL_GL_LoadLibrary().

All uses of SDL_EGL_LoadLibrary (which calls the Only version) are just
target-specific wrappers for their own GL_LoadLibrary hook, with two
exceptions which now handle driver_loaded correctly (although it's
questionable if these init-if-no-one-did-it-correctly-already code blocks
should exist at all, fwiw).

Fixes Bugzilla #5190.

src/video/SDL_egl.c

@@ -438,8 +438,6 @@ SDL_EGL_LoadLibraryOnly(_THIS, const char *egl_path)
     LOAD_FUNC_EGLEXT(eglQueryDevicesEXT);
     LOAD_FUNC_EGLEXT(eglGetPlatformDisplayEXT);
 
-    _this->gl_config.driver_loaded = 1;
-
     if (path) {
         SDL_strlcpy(_this->gl_config.driver_path, path, sizeof(_this->gl_config.driver_path) - 1);
     } else {

src/video/cocoa/SDL_cocoaopengles.m

@@ -109,10 +109,12 @@ Cocoa_GLES_SetupWindow(_THIS, SDL_Window * window)
 
 
     if (_this->egl_data == NULL) {
+        SDL_assert(!_this->gl_config.driver_loaded);
         if (SDL_EGL_LoadLibrary(_this, NULL, EGL_DEFAULT_DISPLAY, 0) < 0) {
             SDL_EGL_UnloadLibrary(_this);
             return -1;
         }
+        _this->gl_config.driver_loaded = 1;
     }
   
     /* Create the GLES window surface */

src/video/windows/SDL_windowsopengles.c

@@ -107,12 +107,13 @@ WIN_GLES_SetupWindow(_THIS, SDL_Window * window)
     SDL_Window *current_win = SDL_GL_GetCurrentWindow();
     SDL_GLContext current_ctx = SDL_GL_GetCurrentContext();
 
-
     if (_this->egl_data == NULL) {
+        SDL_assert(!_this->gl_config.driver_loaded);
         if (SDL_EGL_LoadLibrary(_this, NULL, EGL_DEFAULT_DISPLAY, 0) < 0) {
             SDL_EGL_UnloadLibrary(_this);
             return -1;
         }
+        _this->gl_config.driver_loaded = 1;
     }
   
     /* Create the GLES window surface */