Add derive_gid flag for mounting sdcardfs

Turns on the derive_gid feature for sdcardfs. This was moved
under a mount flag in the kernel.

Test: If the derive_gid flag is supported, the first mount
      should succeed. If the flag is not, the second should
      succeed.
Bug: 63245673
Change-Id: If1c1bce13d14120732e420252cb5605d33ce7c40