ART: minor fix for no-opt debug builds

Works around missing symbol definition for debug builds with no
optimization.

Test: ART_BUILD_HOST_DEBUG=1 ART_BUILD_TARGET_DEBUG=1 \
      ART_DEBUG_OPT_FLAG=-O0 m -j32
Change-Id: I16f2c73855ec49b055e531b91bfdb4450bd0dc8e
1 file changed