Fixed 3783 - Default libGL path for directFB on Linux differs from x11 path

Clayton Craft

The default path used by directfb for libGL is different than the default path used by x11 in SDL2:

./src/video/directfb/SDL_DirectFB_opengl.c:
path = "libGL.so";

./src/video/x11/SDL_x11opengl.c:
#define DEFAULT_OPENGL  "libGL.so.1"

On at least one distro (Alpine Linux), libGL.so is not created (or more accurately the symlink to libGL.so.1 is not created). For consistency, the 'path' variable in SDL_DirectFB_opengl.c should patch the DEFAULT_OPENGL in SDL_x11opengl.c ("libGL.so.1")

src/video/directfb/SDL_DirectFB_opengl.c

@@ -117,9 +117,9 @@ DirectFB_GL_LoadLibrary(_THIS, const char *path)
 
 
     if (path == NULL) {
-        path = SDL_getenv("SDL_VIDEO_GL_DRIVER");
+        path = SDL_getenv("SDL_OPENGL_LIBRARY");
         if (path == NULL) {
-            path = "libGL.so";
+            path = "libGL.so.1";
         }
     }