glx: Don't try to dlopen ourselves

The intention here, long ago, was to ensure that any symbols the DRI
driver needed from libGL were available. We don't have this problem
anymore, libgallium does not import any symbols from the GLX frontend
(or any other one for that matter).

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30417>

src/glx/glxext.c

@@ -1060,22 +1060,6 @@ __glXInitialize(Display * dpy)
 #ifdef GLX_USE_WINDOWSGL
    if (glx_direct && glx_accel)
       glx_driver |= GLX_DRIVER_WINDOWS;
-#else
-#ifndef RTLD_NOW
-#define RTLD_NOW 0
-#endif
-#ifndef RTLD_GLOBAL
-#define RTLD_GLOBAL 0
-#endif
-
-#ifndef GL_LIB_NAME
-#define GL_LIB_NAME "libGL.so.1"
-#endif
-
-   void *glhandle = dlopen(GL_LIB_NAME, RTLD_NOW | RTLD_GLOBAL);
-   if (glhandle)
-      dlclose(glhandle);
-
 #endif
 #endif /* GLX_DIRECT_RENDERING && !GLX_USE_APPLEGL */