FIX: [stereoscopic] fix 3D support for libstagefright and ios

@Memphiz Should work on ios. Could you test, please.

@davilla the fix itself works on Mediacodec, but 3D is "blinking". I guess it is due to:
```
  if (buf.mediacodec)
  {
...
    SAFE_RELEASE(buf.mediacodec);
  }
```
btw, what is the purpose of
```
  for(int i = 0; i < 4; i++)
  {
    tex[i][2] = 0.0f;
    tex[i][3] = 1.0f;
  }
```