Add runpath to lshal_test

android.hardware.test.baz@1.0.so is installed to /data/nativetest(64),
and no longer to /system/lib(64) or /system/lib(64)/vndk, because the
interface library is only for testing.

Set runpath so that lshal_test can find the interface library in the
non-standard directory.

Bug: 65603915
Test: m -j lshal_test
adb push out/target/product/<name>/data/nativetest* /data
adb shell /data/nativetest/lshal_test/lshal_test

Change-Id: I854b08acb6442990ed369bfbc517ad1a93c94584