Fix libarttest to be non debug

Previously both libarttest and libarttestd had debug enabled. This
made it hard to know which one was loaded (couldn't look at
kIsDebugBuild).

Fixes test 136 with ART_TEST_RUN_TEST_NDEBUG configuration.

Bug: 28406866

(cherry picked from commit 48b2b3e5)

Change-Id: I92983f71374b211f96f5b346fec326ea8543f876