Fix link-type warning on GLDual

An sdk app GLDual uses a native:platform library libgldualjni, which
causes a link-type warning. Actually libutils is the only platform
library used by libgldualjni, and the warning can be eliminated by
rewriting code not to use libutils and setting LOCAL_SDK_VERSION.

Bug: 73907534
Test: mma -j does not show any link-type warnings
Change-Id: I2a4f4bb0ac8002cb7ab5c60f8ba74728eca92f22