Fix link-type warning on GL2JNI

An sdk app GL2JNI uses a native:platform library libgl2jni, which causes
a link-type warning. Actually libutils is the only platform library used
by libgl2jni, 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: I76cb1ea579a7cf091852cd3f7ceadb781d33ea4a