Add LOCAL_SDK_VERSION := current

The nativetesthelper is using only public API. However it is defined
java:platform which can use internal API, since it is not
defined LOCAL_SDK_VERSION.
So, LOCAL_SDK_VERSION := current is added in nativetesthelper, because
it can be turn into errors when link type check becomes more strict.

Bug: 69899800
Test: mma -j under nativetesthelper dir
Change-Id: Ia109cd36993d6214e03aec11bb207749da9f58f7
1 file changed