egl: Allow binding to any client API.

As a result, EGL_NONE is no longer a valid client API.  And it is
possible that no config supports the current bound API.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>

src/egl/main/eglglobals.c

@@ -15,7 +15,6 @@ struct _egl_global _eglGlobal =
    &_eglGlobalMutex,       /* Mutex */
    NULL,                   /* DisplayList */
    1,                      /* FreeScreenHandle */
-   0x0,                    /* ClientAPIsMask */
    0,                      /* NumDrivers */
    { NULL },               /* Drivers */
    2,                      /* NumAtExitCalls */