android: build with libcxx on android lollipop

On Lollipop, apparently stlport is gone and libcxx must be used instead.
We still support stlport when building on earlier android releases.

Signed-off-by: Chih-Wei Huang <cwhuang@linux.org.tw>
Reviewed-by: Eric Anholt <eric@anholt.net>
5 files changed